Glossary

  • 4-track
    A film soundtrack format used for overseas markets. Called a completely filled mix, the four-track stereo M&E mix is ready for the addition of dubbed languages. The M&E tracks should include background sound effects and room tone for every scene, i.e., all sound except dialog.
  • 5.1-channel format
    A digital, discrete six channel mix of Left/Center/Right/Left surrond/Right Surround/ Subwoofer mix. 5.1 is not a specific surround format tied to any particular company or codec. However, all the hardware is the same for any 5.1-based system except for the codec. It is planned that CDs, laserdiscs, and DVDs will have an ID flag to let the decoder know which codec was used, enabling decoders to recognize all incoming bitstreams and automatically switch modes and process the incoming signal appropriately. It is a listening platform and hardware concept for a surround loudspeaker system. See DTS, Dolby Digital, HDTV, CDS, LFE.
  • A
    The left-hand part of a stereo signal. Also known as L.
  • A-2
    See Voice of the Theater.
  • A-3
    Dolby laboratories' low-bit-rate codec system used in its Dolby Digital format film, in both broadcast and consumer video formats.
  • A-4
    See Voice of the Theater.
  • A-7
    See Voice of the Theater.
  • A/B
    A comparison between two recordings of the same material; pre- and post-equalization, or pre- and post-effects, or any other comparison between two similar audio devices.
  • A-chain
    The part of the motion picture reproduction system in a theater that contains the sound transducer (such as an optical analog track reader or digital sound format decoder), preamp, noise reduction, and matrix decoding, where applicable. The A-chain equipment decodes the sound in preparation for the B-chain and loudspeakers.
  • Daisy chain
    See serial(2).
  • A-DAM
    Akai Digital Audio Multitrack. A format developed by Akai in 1987 for recording twelve tracks of digital audio data on a standard Video-8 cassette and which allows the synchronization of multiple decks for 24- or 36-track recording. The tape runs at four times the normal Video-8 speed and gives about 15 minutes of recording time at 44.1kHz.
  • A.I.R
    Always In Record. The practice in a recording session to record virtually everything on the off-chance that something which was not formally recorded as a take will be useful.
  • A-roll
    Film footage used to introduce or provide backup material for a live video broadcast.
  • A-track
     The primary dialog track cut by the picture editor. The B-track and subsequent tracks would be used for overdubs.
  • A-type
    See Dolby noise reduction.
  • A-weighting
    An equalization curve first applied to sound level meters in an attempt to make their measurements correspond better to the perceived loudness of sounds, decreasing the sensitivity of the meter to frequencies below 1kHz. An important note is that the bottom octave (32Hz) is attenuated by almost 40dB; the second octave (63Hz) by 26dB, and the third octave (125Hz) by 16dB. See B-weighting, C-weighting, equal loudness curves, SPL.
  • A440
    See concert pitch.
  • AAC
    Advanced Audio Coding. A flexible streaming format that supports multichannel audio including subwoofer and embedded data channels, using a variety of sample rates up to 96kHz. AAC is being developed as a successor to MPEG-2.
  • Aachen Head
    A binaural microphone developed by Head Acoustics.
  • AAF
    Advanced Authoring Format. A cross platform interchange format used in the creation, editing, and distribution of media content in an all-digital environment.
  • AB recording
    In the US, this means recording with a spaced pair. In Europe, this means recording with a coincident pair.
  • AB-reel
    Term for a 23-minute or 2,050’ maximum reel of film specially made for theater screening. The AB-reel may originally have been made from two 1,000’ edit reels; "Projection reel 1AB" would have been originally been reel #1 and reel #2 during editing and mixing. (In the event that the total footage of the first three editing/mixing reels added up to less than 2,050’, there may be a projection reel "1ABC," but this is rare.) It is becoming more commonplace to edit films in AB reel format as the magnetic film units are gradually replaced with DAWs. AB-reels are also known as "big reels" or "2,000-foot reels." AB-reels are not the same as A/B-rolls, in which the camera negative is checkerboarded into two strands, allowing for simple optical effects such as fades and dissolves to be made when making original-negative prints (see EK Negative) called interpositives. This latter process is not limited to two (A, B) rolls, but can involve as many rolls of film as desired, e.g., a camera negative cut in four strands would have a "D-roll."
  • ABS
    Absolute time. Timecode which is the actual running/recording time in HH:MM:SS, where 00:00:00 is the head of the tape. For example, DATs use ABS timecode. See also feet/frames.
  • Absorption coefficient
    The ability of a material to absorb, rather than reflect, sound waves. A higher absorption coefficient means better acoustical damping. See bass trap, boundary effect, standing wave, Sabins.
  • AC
    Alternating current. The current flows in both directions.
  • AC-1
    A form of ADPCM(Adaptive Delta (Differential) Pulse Code Modulation). It was first used in 1985 for digital radio (sound-only) applications and since adopted for other DBS (direct broadcast satellite) services, including soundtrack-with-video, satellite communication networks, and digital cable radio systems. AC-1 has a data rate between 220 kbps and 325 kbps.
  • AC-1
     A form of ADPCM(Adaptive Delta (Differential) Pulse Code Modulation). It was first used in 1985 for digital radio (sound-only) applications and since adopted for other DBS (direct broadcast satellite) services, including soundtrack-with-video, satellite communication networks, and digital cable radio systems. AC-1 has a data rate between 220 kbps and 325 kbps.
  • AC-2
    A transform encoding/ decoding scheme for audio compression developed by Dolby labs that uses 256-band transform coding at a data rate of 128 kbps or 192 kbps on two channels. Used in the Dolby Fax System and also DP5xx encoding.
  • AC-3
    A multichannel, digital, split-band, perceptual coding scheme developed by Dolby Labs. It produces a 5.1 channel format, using lossy compression. Designed to be the matrixing format for DVD and surround-sound with HDTV broadcasts. Versatile, in that parameters such as bit-rate and number of channels can be tailored to particular applications, unique in that AC-3’s data bits are distributed dynamically among the filter bands as needed by the particular frequency spectrum or dynamic nature of the program. Data rates vary from 32 kbps for a single mono channel to as high as 640 kbps for 5.1 format. See Dolby Digital.
  • AC bias
    See bias.
  • AC coupling
    Coupling between electronic circuits that passes only time-varying signals (i.e., alternating current), not direct current.
  • AC-M
    A newly developed codec based on a soft data compression ratio of between 2:1 and 3:1. Used in the Dolby Digital Dubber, it is designed specifically to record eight tracks of 20-bit material on removable media, including Iomega Jaz and MO drives. AC-M is said to be optimized for multiple record/replay generations. Initial tests have reported as many as 14 codec processes being possible with no audio degradation.
  • ACA
    Active Combining Amplifier. See combining amplifier.
  • Academy centerline
    See optical track.
  • Academy curve / Academy sound
    The name of the standard mono optical track that has existed since the beginning of sound on film. Standards were codified in 1938, although the standard has changed somewhat through the years. The standard specifies a flat response throughout the range of 100Hz-1.6 kHz and is down 7dB at 40 Hz, 10dB at 5 kHz, and 18 dB at 8 kHz. Also called an N-Curve. See also X-Curve.
  • Academy leader
    The visual countdown that precedes the first program frame of a motion picture. Symbols and numbers on the academy leader are used for aligning the various film reels and the optical track for composite printing, for aligning the workprint and edited soundtracks for mixing, and for timing the change-over from one reel of film to another during projection. Academy leader contains one number per foot following the Picture Start, with 11, 10, etc., leader to three. (As projected, these numbers appear upside-down.) Named after the Academy of Motion Picture Arts and Sciences, which sets all film format standards. See also leader, SMPTE Universal leader, plastic leader, fill leader, LFOP.
  • Academy Theater
    Specifically, the Samuel Goldwyn Theater at the Academy of Motion Pictures Arts and Sciences on Wilshire Boulevard in Los Angeles, considered the best-sounding theater in the world. Academy members screen films at the Academy Theater prior to voting on them for the Oscar awards.
  • Accelerando
    An indication that the tempo of a piece of music should gradually be increased.
  • Acceptance angle
    The usable working area in front of a microphone is defined by the polar pattern and is called the acceptance angle.
  • Accidental
    In a musical scale, the accidentals are the extra sharp and flat notes that are not part of the diatonic series. For example, in the key of C on the piano, the accidentals are the black keys.
  • Acmade
    The British manufacturer of edgecoding machines.
  • Acoustic baffle
    See baffle.
  • Acoustic baffle
    A partition placed between two sources of sound, or between a sound source and a microphone, to prevent sound from passing through. The baffle, or screen, may be made of any material with a high absorbtion coefficient. Most baffles are designed as movable partitions, and are used to isolate individual instruments in recording studios.
  • Acoustic feedback
    A squealing sound when the output of an audio circuit is fed back in phase into the circuit’s input. See feedback.
  • Acoustic intensity
    The power carried by sound waves per unit area in a direction perpendicular to that area. See sound pressure level.
  • Acoustic labyrinth
    (1) A type of design for the housing of highly directional microphones that enhances the rejection of off-axis sources. Two or more concentric tubes in front of (and sometimes around) the capsule create a compact series of folded pathways through which all sounds approach the diaphragm. Those arriving on-axis reach the capsule via these paths in phase coherence. Off-axis sounds, due to the different lengths of the passways, reach the diaphragm and are partially or fully removed due to phase cancellation. (2) A type of speaker enclosure in which sound waves emanating from the rear of the woofer cone travel through a long, folded interior path before coupling with the outside. This extends bass response considerably.
  • Acoustic lens
    A device placed in front of a high-frequency speaker that disperses or directs the sound in the desired pattern. Normally used to increase the angle of dispersion, either horizontally, vertically, or both.
  • Acoustic suspension
    A loudspeaker designed for, or used in, a sealed enclosure. Typically, a low-frequency loudspeaker baffle where most of the damping of the cone is the result of the elasticity of the air in the sealed cabinet.
  • Acoustics
    The science or study of sound and its interaction with the human hearing mechanism.
  • Active
    (1) An audio device that requires a power source such as from an AC line or battery, as opposed to passive. Sometimes amplifying components such as transistors or ICs are called active circuit elements. (2) See MIDI patchbay.
  • Active crossover
     See crossover network.
  • Active equalizer
    An equalizer that employs active components such as transistors or ICs in its processing circuits. A pre-amplifying circuit generally follows each stage of actual equalization, boosting the signal level to restore unity gain. See also passive equalizer.
  • Active monitor
    A type of loudspeaker that has amplification circuitry built-in. In addition, a true active monitor system utilizes active equalization and active crossovers to precisely contour the system sound. If there is only one amplifier driving all transducers, and/or there is no active equalization or crossover circuitry, the terms powered speaker or powered monitor are preferred.
  • Active sensing
    A MIDI system message that carries no note data or control instructions, but simply indicates to a receiving device that the MIDI line is in working order.
  • Adagio
    A slow or leisurely tempo: 66-76 bpm.
  • ADAT
    Alesis Digital Audio Tape. A second-generation (1992) MDM. An 8-track, S-VHS-based digital audio recorder. Like the Tascam DA-88, ADAT systems record digital audio on consumer videocassette formats and provide for interlocking up to 16 8-track, rack-mount recorders in sample-accurate (48kHz) sync for up to 128-track recording. ADAT is a 16-bit format, currently supported as well by Panasonic, using T-180 S-VHS tape. ADAT-II is a newly proposed 20-bit S-VHS format used by newer Alesis and Studer 8-track recorders. See also DTRS.
  • ADB
     Apple Desktop Bus. The original serial interface for the keyboard, mouse, and other "desktop" peripherals on Apple computers. ADB has been replaced by USB.
  • ADC
    Commonly abbreviated A/D converter or just A/D. A device that changes the continuous fluctuations in voltage from an analog device (such as a microphone) into digital information that can be stored or processed in a sampler, DSP, or digital recording device.
  • Additive synthesis
    The generation of complex musical waveforms in electronic synthesizers by the linear addition of sine wave components whose frequency relationship is a harmonic series. See sample synthesis, sound synthesis, subtractive synthesis.
  • Address track
    A control/timing track on the edge of videotape (1", C, and 3/4" formats) that contains control data for quick and accurate location of program material, recorded at the same time as the picture. See control track.
  • Adjustable turnover
    A variable tone control in a preamplifier which allows the adjustment of the boost/cut and the frequency below or above which the gain/attenuation is applied (turnover), but not the rolloff slope of the shelving equalizer. If it were possible to adjust the rolloff slope, the result would be a fully parametric tone control.
  • ADL
    Audio Decision List. ADL is also known as AES 31. It is an edit data exchange format for audio mixing and workstation. This ASCII based design provides sample accurate editing. It also includes file locators within a structure to support exchange between disk based audio systems The ADL or AES31 is officially titled: "AES standard for network and file transfer of audio — Audio-file transfer and exchange Part 3: Simple project interchange.
  • ADPCM
    Adaptive Delta (Differential) Pulse Code Modulation. A type of split-band, time-domain audio compression algorithm for 16-bit digital audio based on describing level differences between adjacent samples. Different from conventional linear PCM by coding only level differences between samples, rather than the absolute level of each sample. According to the characteristics of the audio signal, ADPCM adapts the step size represented by each quantizing interval to accommodate rapid changes in level caused by high frequencies or transients, thereby providing an overall reduction in bit rate; the compression ratio is 4:1. There are at least two ADPCM standards: Microsoft and IMA/ADPCM, the latter popular for multimedia applications. See delta modulation, split-band, sub-band, transform coding.
  • ADR
    Automatic Dialogue Replacement. Recording of dialog for a scene after it has been shot, usually to replace location sound that is unusable because of street noise, camera noise, etc. The workprint and sync magnetic film transfer for the scene are spliced into continuous loops and projected in a sound studio so that the actors can recreate the phrasing and feeling they had on the set. New takes are recorded on a separate mag film loop and/or other synchronous tape until an acceptable performance is obtained. Also see virgin looping, looping, and lip sync.
  • ADSL
    Asymmetric Digital Subscriber Line. A high-speed Internet connection that’s called “asymmetric” because it’s capable of much faster downloads speeds than upload speeds. It is faster that ISDN but cheaper than T-1.
  • ADSR
    Attack/Decay/Sustain/Release, the four segments of a common type of sound synthesizer envelope. The controls for these four parameters determine the duration (or in the case of sustain, the height) of the segments of the envelope. Two additional parameters, D (Delay Time) and H (Hold Time) are available on some synthesizers. See envelope, envelope generator.
  • ADT
    Auto Double Tracking. An effect produced by taking a track and copying the material onto another track, delayed by a few ms, then mixing it with the original. Like chorusing, but with a shorter delay. See also double-tracking.
  • AES
    Audio Engineering Society. The professional organization whose members report on new technological developments in audio, and bring together designers, manufacturers, and users of various audio equipment to establish international standards.
  • AES/EBU
     Audio Engineering Society/European Broadcast Union. A standard for encoding multiple channels of digital audio along a serial cable, officially named AES3-1985. The standard specifies usually uses 3-pin XLR jacks and balanced line cables, usually running at +4dBm. Originally designed as a self-clocking system, a subsequent addendum to the specification permitted master clock systems. Two channels of digital audio data are multiplexed on a single conductor within the cable, with a maximum bit depth of 24 bits. Data are transmitted at 64 times the sample rate, allowing the possibility of sending two channels of 24-bit audio (plus ECC) to play the resulting stereo signal in real-time. AES/EBU does not carry the SCMS copy code, and is a self-clocking protocol. It has been adopted by the EIAJ, which calls it the CP-340, Type 1. See also S/PDIF.
  • AES31
    Standard for network and file transfer of audio: Audio-file transfer and exchange. A file format that can be converted to AAF lossless-ly. However this file structure is not as deep as that of AAF and file transfers from AAF to AES31 are lossy
  • AF
    Audio Frequency. This refers to frequencies within the audible range, usually taken to be 20Hz-20kHz. This frequency range is an average; many people hear tones below 20Hz, although most people are virtually deaf above 15kHz or 16kHz. See Hz (Hertz).
  • AF
    Alternative Frequency. See RDS.
  • AFM
    (1) Audio Frequency Modulation. A processing scheme used for recording high-quality analog audio in video cassette recorders equipped with "Hi-fi" stereo audio. (2) American Federation of Musicians. The union that represents professional musicians in all their client and employer relations.
  • After-fader listen
    (AFL) On many recording and mixing consoles, there is an option labeled AFL, or after-fader listen. This allows the listener to hear the audio after the channel fader has effected the audio signal. The AFL is also known as post-fader listen. The oposite of AFL is pre-fader listen.
  • Aftertouch
    A type of MIDI controller data, generated by pressing down on one or more keys after they have reached and are resting on the keybed. Also called pressure. See channel pressure, poly pressure.
  • AFTRA
    American Federation of Television and Radio Artists.
  • AGAC / American Guild of Authors and Composers
     A third performing rights organization similar to ASCAP and BMI but much smaller. AGAC primarily represents modern classical composers.
  • AGC
     Automatic Gain Control. See AVC.
  • AGP
    Advanced Graphics Port. A dedicated high-speed interface between PC memory and a graphics card and monitor. Before AGP existed, graphics cards were fitted into standard PCI slots and could cause audio clicks and pops if they didn’t correctly release the PCI buss for other duties when requested, thereby preventing audio data from reaching a PCI sound card. Nowadays all PCs use AGP graphics technology, which provides faster graphics performance and avoids such audio interference problems. As an aside, music applications don’t use 3D graphics, so musicians don’t need an expensive state-of-the-art graphics card. Far more useful is a good-quality 2D dual-head model that supports two monitor screens, since most music software will let you place the song’s arrange page on one screen, and the software mixing desk on the other, which makes working with complex multi-track songs far more pleasurable.
  • Aharmonic
    Containing frequencies that are not whole-number multiples of the fundamental. See harmonic, partial, clangorous, inharmonic.
  • AIFF
    Audio Interchange File Format. A common Macintosh audio file format. It can be mono or stereo, at sampling rates up to 48kHz. AIFF files are QuickTime-compatible and support uncompressed mono, stereo, and multichannel audio at many different resolutions and sampling rates, including the CD standard. It was designed to serve as a universal interchange format that allows any program to open a digital recording created by any other program. AIFF is high-quality audio, used in pro-level Mac and PC audio software. As AIFF is a standard for uncompressed audio, Apple introduced AIFF-C which can use MACE and IMA/ADPCM compression with ratios as high as 6:1, but the audio sound quality suffers.
  • AIM / Amplitude Intermodulation Distortion
     Intermodulation distortion where one signal will cause amplitude modulation of another signal.
  • Air pressure mic
    Also known as a Velocity Mic, which converts sound waves traveling in air into an audio signal that travels through the mic cable.
  • Air suspension speaker
    A sealed enclosure. Typically, a low-frequency loudspeaker baffle where most of the damping of the cone is the result of the elasticity of the air in the sealed cabinet.
  • Airline version
     A remixed and possibly re-edited version of a film that has any objectionable material removed. The airline film standard is more stringent even than those of the broadcast networks, and is often used as a benchmark for TV viewing.
  • Algorithmic composition
    A type of composition in which the large outlines of the piece, or the procedures to be used in generating it, are determined by the human composer while some details, such as pitches or rhythms, are created by a computer program.
  • Alias
    A file on a Mac that serves as a pointer to another file. The most common use for an alias is to sit on a desktop or in a top-level folder, where the real document or application file is nested deep within the file system. This is similar to a shortcut file on a PC-type computer.
  • Aliasing
     Distortion that is produced when higher harmonic components of the input audio signal sampled by a digital recording device, or generated within a digital sound source, lie above the Nyquist frequency. This happens when the sampling rate is less than twice the frequency of the signal being sampled. The effects of aliasing differ from some other types of distortion in that its pitch changes radically when the pitch of the intended sound changes. Also called foldover. See anti-aliasing filter.
  • Alignment
    (1) In tape recording, the process of adjusting all parameters of the position and orientation of the tape heads and guides with respect to the tape path. See azimuth. (2) The adjustment or calibration of any parameter of an electronic circuit or device, e.g., program level, bias level, to bring this parameter into conformance with an industry standard. (3) The process of matching mixer and recorder meters so that only one meter needs to be watched during recording. When the mixer and (analog) recorder are both peaking about 0VU, this minimizes the noise and distortion in both units. Ideally, both units would be matched with a steady tone (the C or B two octaves above middle-C, or about 2kHz, for example.) See line-up tone.
  • Alignment recording
    A tape loop of audio silence, processed by a recorder with some kind of noise-reduction enabled, such as Dolby-SR (where it is called SR noise) or dbx or dB. Used to check equipment for ground loops or other problems in recordings and/or masters. See Dolby noise. See biased noise.
  • All-Notes-Off
     A MIDI command, recognized by some but not all synthesizers and sound modules, that causes any notes that are currently sounding to be shut off. The panic button on a synth or sequencer usually transmits All-Notes-Off messages on all 16 MIDI channels.
  • All-pass Network / Filter
    An electrical circuit with a uniform amplitude response versus frequency response, but with a phase-shift which does not vary in a linear relationship with frequency. (A pure time-delay device such as a digital delay line will have a phase-shift which is directly proportional to frequency, i.e., its phase-shift increases at a constant rate with frequency.) Complex filters often have significant phase distortion because they are not phase linear, and an all-pass network can be designed to correct phase anomalies without affecting the amplitude response.
  • Alla breve
    A term historically related to mediæval note lengths, in which the breve was one of the shortest notes. In modern usage, the term is usually used to denote 2/2 (cut-time). In commercial and popular music, it is frequently used to mean half-time, i.e., play twice as fast. See time signature.
  • Allegro
    A lively to reasonably fast tempo: 116-150 bpm. Allegretto is a slightly slower tempo than allegro.
  • Alternating current (AC)
     An electrical current that periodically changes in direction. The rate of alternation is called the frequency and is measured in cycles per second or Hertz. Audio signals are always alternating, the frequency corresponding to the pitches of the sounds the signals represent. See Appendix.
  • AM suppression
    The ability of an FM tuner or receiver to reject amplitude modulation of the received signal and be sensitive only to frequency modulation. Much of the interference and noise in broadcasting appears as amplitude modulation, so a tuner with good AM suppression will have less distortion and noise than a tuner with poorer suppression. Also called AM rejection.
  • Ambience
    Ambience refers to the acoustical qualities of a listening space, such as reverberation, echoes, background noise, etc. On most music recordings, some of the ambience is recorded along with the music and are, to a certain extent, reproduced in the listening environment, e.g., an organ in a cathedral. See room tone, walla, NC Curve.
  • Ambience track
    An edited roll of magnetic film, or one track of a multitrack tape, assembled by the sound editor in preparation for the final mix of a motion picture or video production, containing the series of room tones or ambient sounds of the various sets and locations in which a scene was shot.
  • Ambient noise
     Ambient sound which is environmental in nature, such as traffic noise coming through walls, heating or air conditioning, or other extraneous sounds which cannot be turned off or removed.
  • Ambient sound
    Sounds such as reverberation, room tone, walla and atmospherics that form a background to the main sound, usually in the context of a film soundtrack of a motion picture, taking place at any given moment. The lack of ambient sound is noticeable because the human hearing system expects it. See also ambient noise.
  • Ambisonics
    A system for the reproduction of a three-dimensional sound field, using two or more transmission channels and four or more loudspeakers. See Soundfield microphone.
  • AMEI (Association of Music Electronics Industries)
    A group that works with MMA on MIDI standards, among other things.
  • Amp simulator
    A filter circuit that mimics the amplifier and loudspeaker voicing of an electric guitar and amplifier system.
  • Ampere (A)
    The unit of measurement for electrical current in coulombs (6.25 x 10^18 electrons) per second. There is one ampere in a circuit that has one ohm resistance when one volt is applied to the circuit. One should not speak of the "flow of current." The current exists; the charge flows. This is analogous to the current in a river, which consists of the flow of water.
  • AMPEX
     A former manufacturer of videotape recorders, analog audio tape recorders, and associated magnetic tape media. For the historic trivia fan, AMPEX is an acronym based on the founder’s name, Alexander M. Poniatoff Excellence.
  • Amplifier
    An electrical circuit or device designed to increase the current, voltage, or power of an applied signal. An amplifier is an active device and, strictly speaking, should always increase the power of a signal; some amplifiers, such as certain distribution amplifiers, may only reduce the impedance level of the signal for the purpose of driving long lines.
  • Amplifier gain
    The amount of amplification that an amplifier provides is called its gain. The gain is a ratio of the input signal level to the output signal level and is simply a number. Commonly expressed in dBindB, one should not express the voltage gain of an amplifier in dBindB unless the input and output impedances are matched as the gain of a typical amplifier is not related to its power output capability. For instance, if an amplifier has a voltage gain of 10, it might be said that it has a gain of 20dB because it actually would raise the power level of a signal by 20dB if the input and output impedances were matched. In practice, however, this is very seldom the case, and the true power gain is usually very much different from what would be predicted by the voltage gain. See impedance matching.
  • Amplitude
     The relative strength (amount) of a signal, without regard to its frequency content. Amplitude is measured by determining the amount of fluctuation in air pressure (of a sound), voltage (of an electrical signal), or numerical data (in a digital application). When the signal is in the audio range, amplitude is perceived as loudness. Amplitude is the measurement of how much energy the sound has, i.e., the total change in air pressure during a single cycle of the sound wave. Amplitude, or sound pressure, is measured in a scale called decibels (dB). An increase of 3dB is equal to a doubling of a sound’s pressure. Amplitude can be expressed as either a negative or positive number, depending on the signals being compared. See also magnitude, SPL.
  • Amplitude errors
    See frequency response errors, jitter.
  • Amplitude Modulation (AM)
    The instantaneous amplitude modulation of one signal by another. This results in the formation of sidebands which contain the same information as the original signals, but translated upwards and downwards in frequency. In AM radio transmission, the audio signal is combined with a very high-frequency sine wave, called a carrier, in such a way that the amplitude of the carrier is varied in exact response to the amplitude and frequency of the signal. This is called the amplitude modulation of the carrier. The modulated carrier is transmitted at high power where it is received by radio sets that are tuned to the carrier frequency. The modulated carrier is then demodulated by a process called detection, recovering the original signal. In radio, a circuit that does amplitude modulation is also called a heterodyne.
  • Anacrusis
    a special case of offbeat which immediately precedes the first beat of the bar, and hence the bar line. See beat
  • Analog
    Capable of exhibiting continuous fluctuations. An audio signal is an electrical replica, or analog, of the waveform of the sound it represents. The voltage of the signal varies up and down (negatively and positively, in electrical terminology) the same way as the sound pressure varies up and down at the microphone. In an analog synthesizer, such parameters as oscillator pitch and LFO speed are typically controlled by analog control voltages rather than by digital data, and the audio signal is also an analog voltage. Compare with digital.
  • Analog recording
    Any method of recording in which the recorded waveform is a continuous representation of the original signal, e.g., conventional magnetic tape recording.
  • Analog sequencer
    A sequencer into which sounds for storage and playback are fed as analog signals, via analog potentiometers.
  • Analog synthesis
    The technique of arriving at the desired timbre by filtering waveforms rich in harmonics. Subtractive synthesis is the type generally used on analog synthesizers. This works well on good analog synthesizers, but when used on samples, reducing the number of harmonics usually just makes the sound flat and lifeless.  See subtractive synthesis.
  • Analog-to-digital converter
     Commonly abbreviated A/D converter or just A/D. A device that changes the continuous fluctuations in voltage from an analog device (such as a microphone) into digital information that can be stored or processed in a sampler, DSP, or digital recording device.
  • Anamorphic
    The camera/projector lens system which squeezes an image, usually originating in a 2:1 aspect ratio) onto film during shooting and "unsqueezes" it during projection. The resulting viewed image has an aspect ratio twice as wide as what was originally recorded on the film, e.g., if the image on the print is 2.2:1, the screen image will be 2.4:1. See also CinemaScope, flat(4), ‘scope.
  • Andante
    At a "walking" speed: 76-94 bpm. Andantino can mean either a little faster or a little slower than andante, although it more commonly denotes a little faster.
  • Anechoic
    Without echo. Said of an acoustic which is free-field, and specifically of a room which is designed to produce no reverberation or other echo effects. This is achieved by giving the walls very irregular surfaces of considerable and varying depths so that, in theory, all sound waves which strike them are completely absorbed and not reflected. Anechoic chambers are used to test audio equipment and for other types of acoustic and electromagnetic electro-magnetic research.
  • Anhysteretic
    See hysteresis.
  • Anode
    The anode in any electronic component, such as a silicon diode or a vacuum tube, is the electrode normally connected to the positive voltage.
  • Answer print
    The first composite print made from the edited picture negative in 35mm film, or the A- and B-rolls of a motion picture in 16mm. Each shot is exposed, color-balanced, and otherwise processed. Further changes and corrections can be made in a second or third answer print, if necessary. In many contracts, the delivery of the answer print is specified because it means that post has ended and release printing can begin, although the release print is usually made from an internegative, not the answer print. The answer print is not the same as a black-track answer print which contains no soundtrack.
  • Anti-aliasing filter
    Before a signal is subjected to the process of A/D conversion, it must be passed through a lowpass brick-wall filter to remove any components that are higher than the Nyquist frequency. This is because it requires at least two samples per cycle to determine the existence and strength of a frequency component or the A/D process will create aliased signals. See reconstruction filter, decimation, FIR, IIR.
  • Anti-imaging filter
    See reconstruction filter.
  • Antinode
    A place of minimum sound pressure level in a standing wave, as opposed to a node, which is a maximum level.
  • Antiphase
    A condition where two signals have a phase difference of 180˚, or one-half cycle. It should be called out of polarity, phase being a continuous variable rather than discrete.  See phase reversal.
  • Antiphonal
    A term used to describe music that is played or sung in alternating sections by two separate groups of performers, widely separated.
  • AOR
    Album-Oriented Rock or Adult Oriented Rock. A tendency of some FM radio stations to play longer album tracks.
  • Aperture time errors
    In an A/D converter, the sample-and-hold circuit would ideally take zero time to determine the level of the signal waveform and to hold this level until the next sample is called for. However, it takes a finite time to charge the holding capacitor in the sample-and-hold circuit, and this is called the aperture time. Because the time required to establish a new value of charge depends on the amount of change in the signal level from one sample to the next, the aperture time will vary with the rate of change in signal level, increasing for high-level, high-frequency signals. The starting time of the sampling aperture is also slightly uncertain, and this is called jitter. In other words, lack of precision in the sampling time leads to amplitude errors in rapidly changing signals. The errors involve aperture time, uncertainty in aperture time, and jitter. The result is distortion of the sampled signal which rises with frequency.
  • Apple (�) menu
    The main menu on a Mac, used to access system utilities (such as Keycaps), applications, files, and control panels. This is the equivalent of the Start menu on a PC-type system.
  • AppleScript
     A system-wide macro facility on Macs which gives operating system-level control for compatible applications.
  • APPV
    Audio Post-Production for Video. The process of preparing the individual soundtracks and the final mix for a videotaped production.
  • APRS
    Association of Professional Recording Studios. An industry body set up to ensure a uniform standard of service and practice in the area of sound recording.
  • APRS Tape-Label System
    The APRS has decided on a standard color-code for tape labelling:
  • APT x100
    See ISDN.
  • A&R
    Artists and Repertoire. The department of a record company that selects the performing groups or artists who will be signed to the label, what songs or compositions each artist will record, and who will work with the artist in the production.
  • Aria
    Italian for air (song). Generally indicates a composition for solo voice with accompaniment, also by extension, a lyrical instrumental piece.
  • Arpeggio
    The playing of chord patterns by sounding each note in a sequence, rather than simultaneously. An arpeggiator is a device which will automatically produce arpeggiation, given the parameters which control Direction (up or down or random), a Hold button which allows note patterns to be triggered which keep playing when the keys are released, and a Range control which sets the group of notes to be played over.
  • Arrangement
     (1) A version of a piece of music for resources other than those originally intended. This may be an instrumental version of a vocal number, a piano reduction of an orchestral piece, or may involve altering other parameters of the original, such as its harmony, rhythm, or structure. (2) In sequencers, a term sometimes used for the general layout of tracks, channels, and patches, rather than a complete song. This template can often be saved as a separate file.
  • Articulation
    The way of characterizing notes (usually in a melody) by the precise control of their individual lengths to produce or eliminate gaps between them. The terms staccato and legato reflect the two extremes of articulation. It is one of the most important ways by which music can be shaped into phrases.
  • ASCAP
    American Society of Composers, Authors, and Publishers. The first performing-rights organization formed in 1908, ASCAP collects fees for broadcast of recorded compositions on radio and television, and for live public performances of music and distributes payments to the copyright holders of these compositions.
  • ASCII
    American Standard Code for Information Interchange. The most common encoding for transmitting text data digitally. The code employs 8-bit binary words, by which each letter of the English language, numeral, and symbol is uniquely designated.
  • ASIO
    Audio Stream Input/Output. Steinberg’s protocol for communication between audio hardware and software. Used in Cubase. It bypasses the operating system’s standard multimedia audio drivers to provide multi-channel support, improve audio timing, and reduce monitoring latency. ASIO runs at a lower level (it bypasses much of the Windows OS) and typically manages lower latencies than both MME and DirectSound.
  • Aspect ratio
    The width-to-height ratio of an image. Specifically in film, the format that the film image is intended to be shown in, most commonly expressed as width relative to height, where the height parameter has been scaled to represent 1 unit. Standard TV screens are 1.33:1, films shown in U.S. theatres are 1.85:1, anamorphic films are 2.4:1. Ratios may also be expressed as integers, e.g., the TV ratio may be expressed as 4x3, and widescreen TVs are 16x9, or an aspect ratio of 1.78:1.
  • Asperity
    A small irregularity or imperfection in the surface of a magnetic tape. Low-frequency noise in analog tape recordings caused by asperities produce asperity noise in the recording, a type of modulation noise in that the noise is manifested in the band immediately above or below the program signal. See calendering, dropout.
  • Assemble editing
    Editing of an audio or video program by making a master copy of the various takes, rather than physically splicing pieces of tape together. Virtually all digital editing is done this way. The opposite of insert editing.
  • Assembly
    A collection of selected extracts from original sound rearranged to a desired order. See copy editing
  • Assigns
    Push-buttons on the input modules of a control console that connect, or assign, that particular input to any of the output busses of the console. The signal is routed to the desired tape track of the destination device usually by a matrix of switches in each module of the mixing and/or recording console. This routing process is known as assignment.
  • Asynchronous
    Not according to a fixed rate of repetition. An asynchronous signal can occur at intervals which do not necessarily coincide with a fixed-rate system or master clock pulse.
  • ATA
    See IDE.
  • ATF
    Automatic Track Following. The system used by R-DAT players to ensure that the rotary heads follow the recorded track. This uses a set of signals that is recorded along with the digital data and which are passed to the servo controls to ensure that the tape is correctly positioned with respect to the heads.
  • ATM
    Asynchronous Transfer Mode. A high-speed cell-switching transport standard favored by WAN architects. Used as a LAN networking solution. ATM is capable of getting the job done, but inability to guarantee delivery, tiny fixed frame length and sizeable transmission overhead mean that it is best used for enterprise backbones and WANs.
  • Atmospherics
    See backgrounds.
  • ATR
     Audio Tape Recorder. This is the analog version. A digital audio tape recorder is called a DTR.
  • ATRAC
    Adaptive TRansform Acoustic Coding. A lossy, 5:1-formatsplit-band perceptual coding and compression scheme for reducing data to be written on a MiniDisc. ATRAC offers a 5:1 data reduction ratio in the case of Minidisc, employing the equivalent of 52 filter bands for spectral analysis and quantization. Later versions of ATRAC vary the size of the sample blocks dynamically between 11.6ms and 1.45ms according to the input signal to allow for temporal masking, providing extremely good resulting sound.
  • Attack
    The first part of the sound of a note. In a synthesizer envelope, the attack segment is the segment during which the envelope rises from its initial value (usually zero) to the attack (peak) level (often the maximum level for the envelope) at a rate determined by the attack time parameter. See ADSR.
  • Attack time
     (1) The rate of attack of a note. (2) The time it takes for a compressor or limiter to reduce its gain after a strong signal is applied to it. See release time.
  • Attack transient
    The actual attack waveform. See transient.
  • Attenuation
    The reduction, typically by some controlled amount, of an electrical signal.
  • Attenuator
    A potentiometer (pot or pad) that is used to adjust the amplitude of the signal passing through it. The amplitude can usually be set to any value between full (no attenuation) and zero (infinite attenuation). Pots can be either rotary or linear (sliders), may have discrete dentents (more often in older equipment), and can be either hardware or virtual sliders on a computer screen.
  • AU (.AU)
    An audio file format developed by Sun Microsystems, supported by some PC and Mac audio programs. This format supports stereo and mono files with either 8-bit or 16-bit resolution. It can encode linear files, or use µLaw or ADPCM compression.
  • Audio
     Literally, "I hear" in Latin. The term pertains to any signal, sound, waveform, etc., that can be heard, as opposed to subsonic or ultrasonic sound, radio-frequency signals or video signals.
  • Audio Blank Skip
    Usually accompanies track search and allows the user to skip from the end of one track to the beginning of the next missing out any blank or unrecorded passages on the tape.
  • Audio coding mode
    A parameter in Dolby Digital surround-sound format which refers to the number of channels and their location in for form F/R, where F is the number of front channels and R is the number of rear channels. For example, 5-channel surround is called 3/2 mode, stereo is 2/0, and mono is designated 1/0.
  • Audio enhancer
    Any dynamic signal processing device that in some sense improves a dull or lifeless sound. It can be a simple as EQ or a complex DSP algorithm. Examples of exciters are the Aphex Aural Exciter, BBE Sonic Maximizer, or SPL Vitalizer. Enhancers combine dynamic equalization with either harmonic synthesis or phase manipulation.
  • Audio frequency
    This refers to frequencies within the audible range, usually taken to be 20Hz-20kHz. This frequency range is an average; many people hear tones below 20Hz, although most people are virtually deaf above 15kHz or 16kHz. See Hz (Hertz).
  • Audio silence
    A type of diagnostic recording made with the recording set-up as planned, but with all faders down. Used to make a reference measurement of the noise floor and/or a tape of biased noise.
  • Audio taper
    A type of potentiometer designed for use as a volume control in audio equipment where the resistance varies in a logarithmic, rather than a linear, fashion with rotation of the knob. This gives a better correlation between control rotation and the subjective loudness of the signal.
  • Audio-to-MIDI
     Software or hardware that takes a monophonic instrumental or vocal line, analyzes the pitches, amplitude, and timbre, and converts the line to MIDI notes, complete with pitch-bend, MIDI velocity and volume, and possibly additional controller data.
  • AudioX
    An open MIDI driver specification/standard being promoted by Cakewalk™.
  • Auditory masking
    An audio artifact which occurs when several sounds are mixed, all which occur in the same frequency range. This happens because human ears tend to blend simultaneous sounds into a single, composite sound. When several instruments or other sounds emphasize similar frequencies, those frequencies accumulate and can either become too dominant or can cause one sound to mask another. Synonyms:  frequency masking, auditory masking
  • Augmentation
     (1) The increase of a major or perfect interval by one half-step to make an augmented interval. (2) The appearance of a musical idea in note durations which are longer than those used for its first appearance. This technique was often used in the ployphonic music of the middle ages and renaissance, as well as in contrapuntal music (e.g., fugues) of the baroque and later periods.
  • Aural
    Of, relating to, or perceived by the ear.
  • Auto-assembly
     In on-line editing, the process by which the edit-programmer produces the edited video master tape according to the instructions on the EDL, without human intervention. This is only possible where footage is consistently lit and exposed.
  • Auto-correct
    See quantization.
  • Auto-input
     One of the electronic operating modes of a multitrack recorder. When auto-input is selected, all channels will remain in sel-sync playback mode until the machine is placed in record mode. Any channels that are in "ready " status will then begin recording and will automatically pass their input signals direct to their outputs. When recording is stopped, these channels return to sel-sync playback mode. Also called stand-by mode.
  • Autolocator
    A device for controlling the transport system of a tape recorder, allowing timecodetime code referencing such as SMPTE. Usually a number of locate points can be stored by the device. Some sequencers have an autolocate facility. Also called zero locate.
  • Automatic Volume Control
    A circuit which adjusts the gain of an audio device in inverse proportion to the incoming signal level. An example is a portable tape recorder which is designed for speech recording; when the speaker is close to the microphone, the gain is reduced so as not to overload the tape. Also, a circuit which increases a TV or radio receiver’s gain when it is tuned to weak stations and decreases the gain when it is tuned to strong stations. Called AGC (Automatic Gain Control) in TV.
  • Automation
    A system where manual control of a process is replaced or enhanced by computer control, such as mixing desk automation where faders, mutes, and equalization can be controlled in part or in whole by a computer. In write mode, the automation system produces a continuous record of all the actual fader settings and adjustments made by the engineer during a mix. Most systems allow changes on replay, while remembering and recreating previous manipulations of other tracks. The level changes are recorded and recreated by VCAs in each input module of the console. The VCA-produced data can be recorded directly onto a track of the multitrack tape, giving a continuous record of all mixdown fader settings. Or, the VCA outputs can be recorded onto a separate disk. In the latter system, alignment of the fader data with the multitrack master tape is achieve by referring to a common SMPTE timecodetime code recorded on the tape and disk systems. See mute mode, mute-write, null-point, read mode, snapshot automation, update mode, write mode.
  • Autopanner
     A device for processing a signal so that it can be made to appear at various positions in a stereo image via a remote control or MIDI commands
  • Autostore
    Benefits the long distance driver by scanning the waveband in the area of travel and automatically storing five or six strongest station in order of signal strength.
  • Aux section
     A smaller, independent mixer within the main mixing console which has an output consisting of a mix of everything going into the channels on which the appropriate effects send been turned up.
  • Auxiliary
    An assignable, line-level input with no dedicated input source. Generally refers to an input connector in a preamplifier or integrated amplifier, signal processor, mixer, effects device, etc. The aux input has no de-emphasis or other special equalization and accepts line-level signals. Tone controls onf a preamp usually also affect signals sent to the aux input.
  • Auxiliary
    A bus allowing a signal to be sent from a mixing desk prior to the main output, usually to provide an input to effects. See effects send.
  • Auxiliary envelope
    An extra envelope in a synthesizer that, instead of being hard-wired to a filter or amplitude, is intended as a modulation source that can be applied to various destinations.
  • Auxiliary messages
    A classification of MIDI messages which includes Active Sensing, All Notes Off, Local On/Off, and Reset, and which describes whether the particular MIDI device responds to any of thsese messages.
  • AVC
     Automatic Volume Control. A circuit which adjusts the gain of an audio device in inverse proportion to the incoming signal level. An example is a portable tape recorder which is designed for speech recording; when the speaker is close to the microphone, the gain is reduced so as not to overload the tape. Also, a circuit which increases a TV or radio receiver’s gain when it is tuned to weak stations and decreases the gain when it is tuned to strong stations. Called AGC (Automatic Gain Control) in TV.
  • AVI
    Audio Video Interleaved. Microsoft’s answer to Apple’s QuickTime, and not compatible with Macs.
  • Avid
    A brand of nonlinear video editing system, which, while not being exactly an industry standard, is the most commonly used digital video editing system.
  • Axis
     In microphones, the direction of maximum sensitivity, generally perpendicular to the surface of the diaphragm or ribbon. In loudspeakers, the line projecting through the center of the voice coil toward the listening area. This is usually the direction in which the speaker exhibits the best overall frequency response. See acceptance angle, off-axis, directional microphone, polar pattern.
  • Azimuth
    In a tape recorder, the azimuth is the angle that the gap in the record or playback head makes with the direction of the tape travel, and it must be precisely 90˚ to ensure proper high-frequency performance.
  • B-chain
    The film industry’s term for the sound reproduction system, including amplifiers, crossovers and loudspeakers. See A-chain, chain.
  • B-Channel
    See ISDN.
  • B-format
    A 1" professional video format developed by Bosch. Although generally considered superior to the standard C-format, B-format equipment is used only in a few production and post-production facilities. B-format video masters must be transferred to C-format for broadcast.
  • B inputs
    (1) An additional set of inputs to a mixer channel that allows either additional (but not simultaneous) tracks to be assigned a mixer; (2) More commonly these days, a different source of the same information that appears on the A inputs. This latter technique allows a sound editor to work offline on a sequence while the mixer is adjusting the overall EQ and level in automation while playing back from another copy. The material is recorded to tape, after witching inputs, when the editor is finished.
  • B roll
    See A-roll.
  • B-weighting
    Frequency correction approximately corresponding to human hearing at 70dB SPL. See A-weighting, C-weighting, equal loudness curves.
  • Baby boom
    The nickname of the Dolby 70mm process that dedicates two of the six tracks on a 70mm print to low-frequency information (signals below 250 Hz). This term is no longer used as the new digital multichannel film sound formats specify a dedicated subwoofer track.
  • Back coating
    In magnetic recording tape, a thin coating applied to the non-oxide or back surface of the tape to reduce slippage between tape layers, prevent accumulation of static charge, and minimize curling or wrinkling.
  • Back plate
    In a condenser microphone, the fixed, rigid capacitor element that is charged with an electric polarity opposite to that of the diaphragm.
  • Back timing
    Subtracting the length (in minutes and seconds) of a recorded segment from the time in a longer program at which the segment is supposed to end. If a three-minute segment is to end a 30-minute program, backtiming will indicate that the end segment needs to roll at 27:00.
  • Backbeat
     A musical term referring to the second and fourth beats in a four-beat bar, often emphasized by the drummer.
  • Backfill
    To edit the space between words so that the whole length of a scene, including sections where the take or angle in question is not being used, is contiguous.
  • Backgrounds (BGs)
    Sound effects that sonically define the time and place of a location. Also called ambience, atmos or atmospheres. Backgrounds give a sense of lush sonic effects and placements. More specifically, they usually use pan controls, reverbs, delays, and other positioning tools. BGs are considered sound effects and are not the same as room tone.
  • Backing track
    Pre-recorded music used by a singer or other musician during a performance and which augments or entirely replaces other performers. This has become increasingly popular as musicians attempt to recreate the sound of their studio recordings live on stage.
  • Backing vocals
    In popular music, extra vocal parts which fill in gaps, or harmonize with, the lead vocal line. Usually sung by specialist session singers. Usually abbreviated bvox.
  • Backline
    On-stage instrument amplification.
  • Backward masking
    See temporal masking.
  • BAC&S
     British Academy of Composers and Songwriters. A group being formed among the current Association of Professional Composers, the Composers’ Guild of Great Britain and the British Academy of Songwriters, Composers and Authors, building a larger and more influential "umbrella" organization.
  • Baffle
    A partition placed between two sources of sound, or between a sound source and a microphone, to prevent sound from passing through. The baffle, or screen, may be made of any material with a high absorption coefficient. Most baffles are designed as movable partitions, and are used to isolate individual instruments in recording studios.
  • Bake off
     Hollywood colloquialism for the meeting of the Sound Branch of the Academy of Motion Picture Arts and Sciences in which the members hear ten-minute clips of the seven films that have made the semifinals of the Best Sound Effects Editing award.
  • Bal-unbal
    BALanced-to-UNBALanced. A transformer device used to convert a singled-ended (unbalanced) signal to a differential (balanced) signal. A bal-unbal is essentially a transformer with one leg of the input and output windings hooked together. More complicated devices may also change impendences at the same time. The most common use for a bal-unbal is a 75 ohms coaxial-300 ohms twin-lead converter used in television.
  • Balance
    (1) The amount of relative signal provided to each of two (or more) audio channels. (2) A control on a synthesizer that adjusts the relative volumes of two different sounds which it can voice simultaneously. Not to be confused with pan.
  • Balance stripe
     See mag film.
  • Balanced line
    Audio lines in which the signal current is not carried by the cable shield of a shielded cable. This requires two conductors for the signal, enclosed in a shield, with neither conductor connected to the shield. The circuit utilizes two identical conductors operated so that the voltages on each of them are equal in magnitude, but opposite in polarity with respect to ground. Compare with unbalanced line. See common-mode.
  • Ballistics
    The dynamic behavior of the needle in a meter, such as a VU meter.
  • Band
    (1) An extent along the frequency dimension in which a signal exists is the band. For instance, an octave band is one octave wide. The AF band is 20Hz-20kHz wide. (2) The wider spiraled grooves that separate any two selections on a record. (3) Band is also used to indicate any single selection on a record, cassette, or reel-to-reel tape or CD, i.e., a track.
  • Band-limited
    A signal is said to be band-limited if its frequency content is restricted to a particular frequency range. For instance, the output signal of a CD player is band-limited to 20kHz by the reconstruction filters built into the player.
  • Band masking
    An audio artifact occurs when several sounds are mixed, all of which occur in the same frequency range. This happens because human ears tend to blend simultaneous sounds into a single, composite sound. When several instruments or other sounds emphasize similar frequencies, those frequencies accumulate and can either become too dominant or can cause one sound to mask another. See auditory masking
  • Band part
    A notated form of a piece of music, derived from a full score, usually containing only the music for a single instrument or pair of similar instruments.
  • Band-reject filter
    A filter that discriminates against signals in a specific frequency band. The most common band-reject filters reject a very narrow frequency band, and they are usually called notch filters. The opposite of a bandpass filter.
  • Bandpass filter
    A filter which has both a high-frequency and low-frequency rolloff, and only frequencies in between are allowed to pass. When applied to sound synthesis, a bandpass filter makes the waveform sound like it is coming down a phone line as telephone lines cannot reproduce lows or highs. The opposite of a band-reject filter.
  • Bandwidth
     (1) The capacity of the channel through which information can pass. In audio, the rated bandwidth of a device is the portion of the frequency spectrum it can handle without significant degradation. In digital communications, the bandwidth is the amount of data that can be transmitted in a given period of time. (2) The bandwidth of a bandpass filter is the upper rolloff frequency minus the lower rolloff frequency, i.e., the frequency range in Hertz (Hz), or band, passed by the filter.
  • Bank
    (1) A set of patches. (2) A related set of items, e.g., a filter bank: a set of filters that work together to process a given signal.
  • Bank Select
    A type of MIDI controller message which specifies which bank of (receiving) sequencer programs to use; a way to get around the 128 program limit specified by MIDI.
  • Bantam
     See TT connector.
  • Bar
    In written music, a grouping of pulses into a convenient unit falls between two barlines. A barline is a vertical line that crosses the stave at regular intervals. The bar begins with the downbeat and ends immediately before the next downbeat, and will contain a constant number of beats of the type determined by the time signature, e.g., a bar of 4/4 will have four quarter-note beats.
  • Barkhausen effect
    The tendency of the magnetic elements or domains on a magnetic medium to influence one another and to become magnetized in one direction or another as a group rather than individually. This means that a magnetic medium, such as recording tape, has a graininess in its magnetic makeup which is what causes most background noise, or tape hiss. Modulation noise, which is only present in conjunction with a recorded signal, is also caused by the Barkhausen effect, and is sometimes called Barkhausen noise.
  • Barney
    See blimp.
  • Base
     In magnetic recording tape, the thin ribbon of polyester or other plastic material to which the oxide and back coating are applied, measured in mils. For example, the base of most professional recording tape is 1.42 mils thick.
  • Basic channel
    In a MIDI device, the channel on which the device receives fundamental messages governing its operation, e.g., Reception Mode changes. In Mono Mode, the basic channel is the lowest-numbered channel.
  • Basic track
    The group of instruments or vocalists recorded first during a multitrack session. This group, usually including bass, drums, and standard rhythm section, will be played back through headphones to other instrumentalists who later overdub solos, lead or background vocals, or narration, and other sweetening or sound effects. See also backing track, bed.
  • Basket
    The metal frame of a loudspeaker.
  • Bass
    The very low end of the audio spectrum, approximately 20 Hz -200Hz or 300Hz.
  • Bass build-up
     An increase in molecular pressure variation, not molecular velocity, which occurs at low frequencies at room boundaries. The pressure nodes for all frequencies build up in the corners of rooms, particularly at the intersections of the walls and floor or walls and ceiling. These regions can roughly be thought of as resonant spaces, and energy can be trapped quite effectively by placing frictional absorbers at the desired quarter wavelength out into the room from the corner. See bass trap, boundary effect.
  • Bass trap
     A specially designed low-frequency sound absorber to reduce the effects of standing waves in recording studios. It is a tuned absorber and may have a narrow or wide range of frequencies over which it operates. It usually consists of resonant wood panels with absorptive material behind them, or suitably shaped slots in a wall or ceiling. See bass build-up, boundary effect.
  • Beat
    A regularly occurring pulse that can be heard or implied. (1) When two periodic signals are less than 20 Hz or so apart in frequency, and if they are mixed together, the amplitude of the combined signals will fluctuate as they alternately reinforce and cancel each other. These amplitude fluctuations cause loudness fluctuations and are called beats. See also difference tone. (2) In music, the sensation of a basic pulse from which all rhythm in the piece is derived. Beats are of three types: a downbeat is a strongly accented pulse, such as the first in the bar; an offbeat is any pulse other than the downbeat; an upbeat, also called the anacrusis, is a special case of offbeat which immediately precedes the first beat of the bar, and hence the bar line.
  • Bed
    Background music used underneath a narrator or foreground dialog. Primarily applied to commercial radio or television spots. Also called basic tracks.
  • Bel
    The logarithm in base 10 of the ratio of two different levels of power, acoustic or electric. Since large changes in loudness correspond to fractional portions of a bel, the decibel, 1/10 of a bel, is used as the measurement unit of level for sounds and audio signals. See Appendix A.
  • Bell filter
    A type of filter that allows the boost or attenuation of a specified set of frequencies around a center frequency. Bell filters often allow users to adjust the center frequency, Q, and the amount of boost or cut. Bell filters are sometimes also known as haystack filters.
  • Bench
     In film, the editing table which consists of rewind handling reels holding 35mm pictures and mag film, a sprocketed synchronizer that keeps the reels in sync, in addition to providing a count, and a squawk box. See mut.
  • Bend
     To change pitch in a continuous sliding manner, usually using a pitch-bend wheel or lever. An upward bend is created by pushing away from the front of the modulation controller, and creates an increasing pitch, and vice-versa. See bend depth.
  • Bend depth
    The amount of pitch-shift possible if the pitch-bend modulation controller is moved as far as possible. This is usually set to a whole step, but for special effects (such as electric guitar), it could be set to an octave or more.
  • Betacam
    A professional analog videotape in Beta format, but at an increased tape speed, which gives picture quality comparable with the 1" C format. Betacam also allows separate recording of the red, green, and blue picture information via its RGB mode for computer use. This capability gives much better control of edge-cuts in special effects. Often called Beta for short.
  • Betamax
    A system used for color videotape recording, developed by Sony for consumer systems. Generally acknowledged to give higher picture quality than VHS.
  • BG
     Background. The walla in a commercial or other video production, over which other sound effects, music, and dialog are dubbed. bi-directional microphone : A figure-eight microphone.
  • Bi-phase
    An electronic reference signal used by mag recorders, editing stations, and film projectors. See bi-phase modulation, pilot tone, neo-pilot, and control track.
  • Bi-phase modulation
    In SMPTE timecode generation, the electronic process that produces the signal containing the SMPTE data itself. A 1.2k Hz square wave is momentarily modulated to 2.4kHz with each new bit of location information coming from the master clock.
  • Bi-phase/tach
    An electronic pulse used by some film equipment and other motor-driven devices. Similar to a bi-phase signal, but different in the way directional information is provided. See also tach pulse.
  • Biamp
    Short for bi-amplification. A two-way crossover network.
  • Bias
    (1) Bias is the voltage or current that establishes the intrinsic noise floor of an active device. (2) In an analog tape recorder, bias is an ultrasonic signal, usually between 100k Hz-200kHz, which is mixed with the audio signal and applied to the recording head, reducing distortion by reducing the hysteresis inherent in the tape recording process. This process is known as AC bias because the bias current is alternating. The ideal setting of analog bias involves a compromise between the MOL of the tape, noise, and third-harmonic distortion. In general, classical recordings use a bias setting with lower distortion and lower MOL; rock or other recordings prefer a higher distortion in order to get the highest S/N ratio. Digital recorders do not require bias as the signal consists only of a bitstream of 0s and 1s, regardless of the audio frequency being recorded. (3) See electric microphone.
  • Biased noise
     A tape loop of audio silence, processed by a recorder with some kind of noise-reduction enabled, such as Dolby-SR (where it is called SR noise) or dbx or dB. Used to check equipment for ground loops or other problems in recordings and/or masters. Sometimes called an alignment recording. See Dolby noise.
  • Bin
     (1) A barrel into which strips of film hang, suspended from a row of pins or small nails above. Also called an editing (2) In tape duplication, the container or housing that holds a tape loop to be duplicated.
  • Bin-loop master
     A special tape that is used in cassette duplication equipment. It contains both sides of the tape and is either run at a very high speed or, for higher quality dubs, in real-time.
  • Binaural
    Literally, "having two ears." Because humans have two ears spaced apart by the width of the head, the human hearing mechanism can make use of amplitude, phase (arrival time) and spectral (frequency response) cues to help determine the direction from which a perceived sound is coming. See binaural synthesis.
  • Binaural synthesis
    A type of recording-playback system where two microphone inputs are specially processed to simulate the frequency-dependent time delays that would occur between the ears on a human head. The binaural localization cues are preserved, and the listener is able to achieve localization of sounds as if s/he were actually at the site where the recording was made, despite the fact that binaural recording has no ability to accurately image the sound. Also called dummy head recording.
  • Binder
    A liquid or gelatinous medium in which oxide particles are suspended for application to magnetic recording tape. Usually consists of a solvent that evaporates, and an adhesive substance which that, when dry, permanently bonds the oxide to the base.
  • Binding post
    A type of terminal which allows wires, such as loudspeaker wires, to be connected to the output of an amplifier with alligator clips, banana plugs or bare wire.
  • Binky
    Film sound slang for a mixing "top sheet," indicating the layout and content of the premixes. The layout is usually one column per premix.
  • BIOS
     "Basic Input-Output System." An operating system which resides on ROM and is used to control disk access, exclusively. Used in some samplers and sequencers to control the internal hard drive.
  • Bipolar
    A type of loudspeaker design where the sound emanates from the sides of the monitor, specifically designed to be surround-sound monitors. These type of speakers work well for ambient material, but less well for dialog, soundtrack, or main effect sound. This is opposed to a direct radiator speaker which distributes the sound in front or a tripole design which is a combination of a direct radiator and a bipole.
  • Birdies
    Extraneous high-pitched whistles sometimes present in tape-recorded signals where the high-frequency content of the signal causes beats with the bias signal. Also used to refer to high-pitched interference in AM radio reception.
  • Bit
    Binary digit. The representation of data using base-2 arithmetic, i.e., a series of ones and zeroes. Digital audio is encoded in words that are usually 8, 12, 16, 20 or 24 bits long (the bit depth). Each added bit represents a theoretical improvement of about 6 dB in the S/N ratio.
  • Bit depth
    The number of data bits used to encode each sample point. Bit depth determines the accuracy of a sampler, converter, or other digital device in capturing momentary changes in a sound’s amplitude. Typical bit depth is 16 bits, which is good for capturing loud sounds, but less good for sounds in a quieter range. Also called bit resolution.
  • Bit resolution
    See bit depth.
  • Bit shifting
    A technique for lossless compression which, rather than encoding the entire data word, only bit cells with data (ones) are stored, and the null data (zeroes) are removed. For example, if only 19 bits of a 24-bit word contain data, only those bits are transmitted.
  • Bit-splitting
    A feature on some A/D converters, digital recorders, DAW or other digital devices to choose word lengths to accommodate various output channels, such as a choice between six outputs at 20-bit resolution, or four output channels at 24-bits per sample.
  • BITC
     "Burnt-In Timecode." Video that shows the SMPTE time on-screen in a window along with the picture, eliminating the need to watch a time-code reader. Accurate in still-frame. Sometimes called a "window dub."
  • Bite
    A subjective term for the sharp onset or attack of a musical instrument, especially brass instruments. Excessive bite can result from positioning microphones too close to the instrument or from distortion caused by a momentary overload. See attack transient.
  • Black-burst
    A type of clock reference, this is essentially a video signal without any picture and without any positional information. Also known as house sync. As a black-burst signal is typically distributed throughout a recording/editing facility as the facility master clock due to the extremely accurate clock signal provided. See video black.
  • Black-track print
     A version of the answer print which has no sound, i.e., it is "silent," made from the original camera negative. The first answer prints are usually black-track in order to proceed with the color timing, even though post-production sound has not been finalized.
  • Blacking
    The recording of a periodic signal on a blank video tape which marks the start of each video frame. See video black, video sync, control track.
  • Blanking interval
    The blanking interval occurs at the end of each video frame, during which video information is absent. The interval occurs when the CRT electron gun scanner goes from the bottom-right corner of the screen to the beginning of the next field (4) in the top-left corner.
  • Bleeding
    See crosstalk, channel separation.
  • Blimp
    A solid cover for a motion picture camera, designed to completely contain camera noise. A barney is a padded cover for a portable camera that attenuates but does not eliminate camera noise.
  • Blocking
    (1) The recording of a periodic signal on a blank video tape which marks the start of each video frame. This control track (2) can be used to count time for editing purposes, but is prone to slip and lose count during winding. (3) Plotting actor, camera and microphone placement, and movement in a production.
  • Blue Book
     A CD specification for data, as opposed to sound or video.
  • Blumlein pair
    A stereo miking technique which uses two figure-eight microphones, crossed at a 90˚ angle, set up as closely as possible to one another. This is also sometimes called coincident figure-eights. See also coincident pair.
  • BMI
    A performing rights organization: It collects license fees on behalf of its songwriters, composers and music publishers and distributes them as royalties to those members whose works have been performed. Other performing rights organizations include ASCAP and AGAC.
  • BNC
    (1) Bayonet-Nut Coupler. A two-conductor, low voltage, locking connector most commonly used for the connection of video and high-frequency clock signals. (2) Blimped Newsreel Camera. (ex: The 35mm Mitchell model Camera)
  • Board
    A synonym for a recording console or mixer, a mixing console. (2) Short for a film storyboard.
  • Boom
    (1) In general recording, any sort of microphone stand with extending sections that allows the microphone to tilt and be pointed at a target, such as above a performer or some section of an orchestra, etc. Also called a fishing rod, although the latter usually refers to a lighter-weight rig more suitable for close miking. (2) The LFE in a mix. See baby boom.
  • Boomerang
    To mix a sample with a backward version of itself.
  • Boost
    Boost refers to an increase in amplitude, usually of a specific frequency or within a frequency band range. Equalizers, the most common of which are tone controls, cause boost or cut of selected frequency ranges.
  • Boost/cut control
    A single control which has "no change" at its center-point. If the knob is rotated counter-clockwise, the input is attenuated; rotated clock-wise, the input is amplified.
  • Bootstrap
     An arrangement where the apparent impedance of a circuit element is reduced by applying an appropriate feedback voltage to it, improving the linearity of a circuit, thus reducing its distortion. It is especially useful in circuits that are required to carry a very wide range of power or voltage levels. Used in power amplifier output stages.
  • Bounce
     In multitrack recording, the process of recording several tracks and mixing those sounds down to one or two unused tracks. For example, on an 8-track recorder, you could record six tracks, bounce them down to the two remaining tracks, freeing up the original six tracks for recording use.
  • Boundary effect
    A sound reflection effect due to room modes ( standing waves) which accumulates at walls. sound wave reflections appear to make the localized sound level increase as all of the room modes terminate at the boundary (wall). Essentially as the wavefront approaches the wall, the amounts of molecular motion become smaller and smaller while the pressure differences become greater and greater as the wall resists the motion of the air molecules, the wall becoming a pressure node. The rigidity of the wall surface determines how much the pressure rises, i.e., how much of the pressure is reflected versus how much is absorbed. This occurs on a mode-by-mode basis at each resonant frequency. At very low frequencies, nothing large is rigid. However, at higher frequencies, the boundary effect is more pronounced, e.g., frequencies above 100 Hz in a room with typical walls. A related effect is often observed at a control room window, where the window itself will resonate at one or more resonant frequencies so that the window passes the resonant frequencies through to the (recording) space on the other side, somewhat reducing the boundary effect within the control room, but not providing sound isolation from the adjacent space(s). This last effect is worse for lower frequencies as higher frequencies tend to be absorbed by the glass in the window. Also called the pressure zone effect. See absorption coefficient, bass build-up, bass trap.
  • Boundary microphone
     A boundary microphone uses a small condenser microphone capsule mounted very near a sound reflecting plate, or boundary, so there is no delay in the reflected sound. Direct and reflected sounds add in-phase over the audible range of frequencies , resulting in a flat response, free of phase cancellations, excellent clarity and reach, and the same tone quality anywhere around the microphone. Boundary microphones have a directional response that is either half- omni, half- cardioid or half- supercardioid. An example of a boundary microphone is a PZM (pressure zone microphone).
  • Bpm
    Beats Per Minute. The usual measurement of tempo.
  • Bps
    Bits per second. A metric used to measure the volume of data transferring.
  • Bps
    Bytes per second. The smallest unit of measurement used in data transferring.
  • Break
    In a piece of music, a break is a solo or section of reduced instrumentation, or even complete silence. In modern usage the term usually implies an opportunity for an instrumental solo.
  • Breakjack
    A type of jack socket fitted with switching terminals, so that insertion of a plug breaks an existing connection. Also called a normalled connection
  • Breakpoint
    On synthesizers and samplers, the specific value at which the tracking of scalable parameters, such as velocity, starts to take effect, or at which the nature of the scaling changes.
  • Breath controller
    A device which a performer blows into, bites, or presses with the lips, allowing the articulated sound to be digitally recorded by a synthesizer or sampler. Breath controllers can control volume, filter frequency or amount of LFO. They incorporate a device known as a stress bridge.
  • Breathing
    Audible fluctuations in the noise level of a signal caused by poorly adjusted or unsuitable noise reduction systems which produce a variable changing program level and/or noise floor. Also called pumping, noise pumping or breathing. Pumping is caused by the action of a compressor, occurring when one loud sound source causes severe gain reduction in the compressor. With each loud sound, the level of the other instruments will decrease sharply. Pumping occurs during program material. Breathing, on the other hand, occurs when the program stops long enough for the compressor to cease its gain reduction, suddenly boosting the noise floor of the program. Quantization noise can also exhibit breathing. See also compander.
  • Brick-wall filter
    A very sharp filter which masks any frequency outside the passband, for example, the lowpass filter at the input of an A/D, used to prevent frequencies above the Nyquist frequency from being encoded by the converter. See aliasing, reconstruction filter, anti-aliasing filter, decimation, FIR, IIR.
  • Bridge
    (1) Meter bridge. A structure mounted at the rear of a mixing desk, or on other equipment such as a tape recorder, which contains a number of VU or PPM meters. (2) Bridge mode: a method of driving a single load, such as a loudspeaker, from two similar (ideally identical) amplifiers in order to double the power presented to the load; a stereo amplifier operating at 200W per channel could provide approximately 400W into a single load in bridge mode. Many stereo amplifiers designed for sound reinforcement offer this option. See bridged mono. (3) See bridging. (4) Originally an eight-bar section of contrasting material in the middle of a song, but later applied to a linking section of any length. Also called a bridge passage or middle-eight. See also break.
  • Bridge passage
    A section of music which links two musical ideas. A bridge is usually used to connect movements in different keys and/or tempos. See bridge
  • Bridgeable to mono
    Where the two separate outputs of some stereo amplifiers can be combined to give a mono signal.
  • Bridged mono
    A method of combining both channels of stereo power amplifiers to create a doubly powerful single-channel (monaural) amplifier. See bridge(2).
  • Bridging
    The opposite of impedance-matching. When the input of an audio device is connected to the output of another device, it is a bridging connection if the second device does not appreciably load the first device and essentially no power is transferred. The second device is sensitive to the output voltage of the first device, and this is maximized when the loading is minimized. Most audio connections are bridging, and the load impedance is at least ten times greater than the source impedance. A bridging connection is made by connecting everything in parallel (all the plus inputs connect to the plus output, all the minus inputs connect to the minus output.) This not only allows for a number of loads to be connected to the same source before overloading it, but this also gets the maximum voltage swing possible from the source.
  • Brightness
    The amount of high-frequency signal present in a sound, which tends to make the sound appear closer. The opposite of darkness.
  • Broadband
    Including a wide range of frequencies, generally the entire audio range. Usually used in terms of referring to the broadband performance of an audio device with respect to some specification such as noise, <distortion, etc.
  • Broom
    To discard recorded sound during a mix. Site brooming is when a director rejects a whole group of effects, often the product of several days work.
  • BTSC
    Broadcast Television Systems Committee. The FCC committee that decided upon the MTS standards for stereo television sound in the U.S.
  • BTX
    A brand name of electronic devices that will maintain synchronization between two tape recorders, a tape recorder and a projector or video playback machine, etc. Used primarily to interlock one or more multitrack recorders to a video playback, for purposes of recording, overdubbing, or mixing music in sync with picture. The device uses SMPTE, time code, for electronic control of all machines.
  • Bucking
    The cancellation of one signal or frequency component of a signal by another signal with equal amplitude but opposite polarity. See also phasing, flanging, comb filter.
  • Buffer
    An amplifier with a high input impedance and approximate unity gain. Used, for example, in a mixer at the back panel outputs for headphones and control room monitors to prevent the two loads from overloading the fader output and causing A-rolloff in high-frequency response. A sort of internal distribution amplifier.
  • Bug
    A small contact microphone, designed for string and wind instruments which work along similar lines to a piezo pick-up.
  • Bulk dump
    A System-Exclusive description of an actual sound sent over MIDI.
  • Bulk eraser
    A tape demagnetizer that can erase an entire cassette reel or multitrack tape without removing the tape from its carrier. Essentially a powerful electromagnet. Some bulk erasers have circuits built in that automatically fade the magnetic field up from and ultimately back down to zero. This eliminates pops and other erasure noise normally left on tape if the eraser is suddenly turned on or off. Also called a degausser.
  • Bulk tuning message
    A System-Exclusive message of the non-real-time type that allows the exchange of tuning data between MIDI devices as well as other devices such as computers, allowing microtuning or different temperaments by defining a specific pitch value. The frequency range is from 8.1758 Hz to 13,289.73Hz, in steps of one half-step cents, for each of the 128 notes in the MIDI range. Two messages are involved: a bulk tuning dump request message which is transmitted by a device in order to signify that it is ready to receive, and a bulk tuning dump message which contains the data for 128 tuning programs, each containing 128 pitch values.
  • Bumpers
    Small segments of music in a television or film score that usually precede a dissolve. In television, usually used before commercial breaks. burnt-in timecode time code: See BITC.
  • Bus / buss
    In a mixer, a path via which the user can route a signal from one or more inputs to a specified destination. Typical destinations include: groups, mix, auxiliary send, foldback, etc. For example, "routing inputs 1-8 to the mix bus" means that the eight input signals appear additively at the mix output.
  • Buzz track
    Alignment film used to set the lateral alignment of the optical film recording areas for replay.
  • Bvox
    See backing vocals.
  • BWF
    Abbreviation for Broadcast Wave
  • Bypass
    A facility on an effects unit which allows the user to switch the incoming signal directly through to the unit’s output, cancelling the effect so that an A/B comparison may be made quickly between the wet and dry signal. See wet/dry balance.
  • C.C.I.R
    Comité Consultatif International Radio. An international radio standards committee, whose recommended recording pre-emphasis and post-emphasis curves are standard on all recorders in most European and some other countries. The European analog to the NAB.
  • C-format
    The international standard format for professional 1" videotape equipment. Developed by Sony, and sometimes called S-format after that company’s name. See B-format, Betacam, VHS.
  • C.R
    Con Repeats. As in, "Play from the beginning with repeats" is written, "D.C. (C.R.)."
  • C-Type
    See Spectral Recording, noise reduction.
  • C-weighting
     Unlike A-weighting, C-weighting measures frequencies uniformly over the audio spectrum. An SPL meter will allow the choice of either (or neither) weighting function. See B-weighting, equal loudness curves.
  • Cadence
    A musical punctuation, indicating the end of an idea, or preparing the ground for transition to a new one; essentially a juxtaposition of two chords.
  • Calendering
    To reduce the asperities on the surface of a magnetic tape, the tape is squeezed between large steel rollers; a manufacturing process called calendaring.
  • Calrec Soundfield microphone
    See Soundfield microphone.
  • Cancellation
    See phase cancellation.
  • Canned
    Slang for pre-recorded, as opposed to live music or visuals.
  • Cannon connector
     See XLR.
  • Cans
    Headphones.
  • Capacitance
    See impedance.
  • Capacitor (C)
    A device made up of two metallic plates separated by a dielectric (insulating material). Used to store electrical energy in the electrostatic field between the plates. It produces an impedance to an alternating current. Also called a condenser.
  • Capo
    The beginning of a piece of music. See D.C.
  • Capstan
    In a tape machine, the tape is moved by the effect of friction between a rotating motor-driven pillar, the capstan, and a pinch wheel, also called the capstan idler, that holds the recording tape securely against the capstan when a tape transport is in record or play mode. The capstan motor directly or indirectly drives the capstan and moves the tape past the heads. The capstan itself may be the extended shaft of the capstan motor.
  • Capsule
     In a microphone, the diaphragm or actual sound receptor, including, in various types of mics, the moving coil, ribbon, permanent magnet, or fixed condenser plate, and the housing in which these are mounted.
  • Cardioid microphone
     A directional microphone with an acceptance angle that is most sensitive to sounds coming from the front and sides, while rejecting sounds coming from the rear. Called cardioid because the polar pattern of the microphone is roughly heart-shaped. All directional mics have a proximity effect, whereby sound sources close to the mic will have an exaggerated low-frequency response. Supercardioids and hypercardioids are cardioids, but with a trade-off in the rear lobe. When using supercardioids and hypercardioids as sound reinforcement mics, it is important to note that the maximum rejection is not directly behind the mic as it is with a cardioid, but is off to the side between 110¢ª-126¢ª. However, a pair of hypercardioid microphones used as a stereo X-Y pair yields a very clean cardioid response pattern. See pressure gradient.
  • Carrier
    (1) A signal that is constant in amplitude or frequency and can be modulated by some other signal. The carrier itself does not transmit any information; all of the intelligence is in the modulation sidebands, which are in a band of frequencies on either side of the carrier frequency. Some signals, such as FM stereo, involve more than one carrier to encode the information, and the lower-frequency carrier is called a subcarrier. The subcarrier is mixed with parts of the audio signal and used to modulate the main carrier. In the receiver, the subcarrier is recovered by demodulation of the main carrier and then demodulated to recover its signal. See amplitude modulation, frequency modulation. (2) In FM synthesis, the carrier is the operator at the bottom of a stack in an algorithm, through which the composite effect of other modulating operators connected to it is heard.
  • CAS
    Cinema Audio Society. A Los Angeles-based organization of film and television recording personnel, founded in 1966.
  • Cassette
    A French word meaning "little box." A cassette is a magnetic tape sound recording format. The cassette was originally intended for dictation, but improvements in fidelity led the Compact Cassette to supplant reel-to-reel tape in most non-professional applications. Uses for the cassette include portable audio, home recording, and data storage for early computers. Between the 1960s and early 1980s, the cassette was one of the three most common formats for prerecorded music along with the LP and the Compact Disc. Cassettes consist of two miniature spools, between which a magnetic tape is passed and wound. These spools and their attendant parts are held inside a protective plastic shell. Two stereo pairs of tracks (four total) or two monaural audio tracks are available on the tape; one stereo pair or one monophonic track is played or recorded when the tape is moving in one direction and the second pair when moving in the other direction. This reversal is achieved either by manually flipping the cassette or by having the machine itself change the direction of tape movement ("auto-reverse").
  • Cat. 43
    The Dolby Laboratories device that turns a Cat. No. 22 Dolby A-Type noise reduction card into a 4-band "noise fighter." The precise frequencies of the bands are optimized for production sound problems and differ from those used in standard noise reduction applications. In 1991, Dolby formally introduced SR-type noise reduction, called the Cat. No. 430.
  • Cathode
     The cathode in any electronic component, such as a silicon diode or a vacuum tube, is the electrode normally connected to the negative voltage.
  • CAV
    Constant Angular Velocity: In a mass storage device, such as a disk, CAV means that the disk assembly rotates at a constant speed, i.e., the data rate will increase for the tracks near the edge, and decrease for tracks near the center spindle. As opposed to CLV.
  • CCCC
     See LCRS.
  • CD
    The CD sampling rate is 44.1kHz and there are 32 bits per sample, so the data rate of the encoded analog data is 1.41Mbps, but the inclusion of parity, synch, and subcode bits raises the real data rate to 4.3Mbps. A CD will hold about 650 Mb, or about 74 minutes of stereo, 16-bit audio. The digital portion of the CD audio system is not stereophonic, but sequential monaural. See also Control and Display signals. Compare with Direct Stream Digital. The CD file format is defined by ISO 9660. For more information on CD standards, please see Sound on Sound, "Compact Disc Formats" by Mike Collins, January 1998. See also SACD. (Super Audio Compact Disc.) The CD specification is specified in "books," each defining the standard for a particular type of CD: Blue Book: CD Data (CD Extra) The latest of the books to appear, this specifies the CD Extra format, designed to include CD-ROM data on a standard (audio, Red Book) CD. A CD Extra is actually a multisession CD, containing the audio tracks in its first session, followed by a data track in the second session, etc. Red Book: System Description Compact Disc Digital Audio (CD-DA) CD-DA (Digital Audio) Established in 1980 as the first of the books which defined consumer audio on CD. A Red Book CD may have up to 99 tracks; each track is divided into blocks of data called sectors; each sector contains, in addition to audio data, EDC/ECC, and 98 control bytes of PQ subcodes. Yellow Book: System Description Compact Disc Read-Only Memory (CD-ROM) CD-ROM (Read Only Memory). Yellow Book extends the Red Book specification by adding two new track types: CD-ROM Mode 1: Storage of computer data Mode 1 sectors include an improved ECC for Data. CD-ROM Mode 2: Compressed audio, video, picture data Mode 2 (Forms 1 & 2) CD-ROM/XA (Extended Architecture) is used to integrate computer data with compressed audio and/or video, including Photo CD and Karaoke CD. White Book: System Description Compact Disc Bridge (CD-V) Developed to cover the CD-V (Video) format, and supported by JVC, Matsushita, Philips, and Sony. These are a special kind of CD-ROM/XA bridge disc that allows the play of films and music videos on a dedicated CD-V player, or on a CD-i player equipped with a CD-V cartridge, or a computer with a CD-ROM/XA drive, an MPEG-1 decoder, and host playback application. The CD medium is modified to record video signals as well as digital stereo audio signals. The video information is recorded in analog form rather than digital. CD-V discs contain full-screen, full-motion video and CD-quality audio, and are independent of any broadcast standard, e.g., NTSC, PAL. Green Book: System Description Compact Disc Read-Only Memory Extended Architecture (CD-ROM/XA) Orange Book: System Description Compact Disc Systems Part II: (CD-WO) A digital standard for recordable, write-once CD. The specification covers both disk-at-once and track-at-once. Many older CD-ROM drives cannot read multisession discs, however, these discs can be converted to a Red/Yellow/Green Book disc by adding a TOC, allowing the disc to be read by any CD player. CD Single: A small CD-DA that can record 20 minutes of stereo music; it is 80mm in diameter. CD-DA: CD-Direct Access. Software for writing audio data on hard disk onto a CD-R, for example, Toast™ or Gear.™ Such packages create an unfinished audio session in disc-at-once mode. Digital audio tracks must first be converted to a computer file format like .WAV or AIFF.CD Extra: Formerly called CD Plus. A solution to mixed-mode CDs, CD Extra inverts the track structure of Mixed Mode by creating two separate sessions: first audio, then data. CD Extra is a part of the Blue Book standard, making Blue Book CDs fully compatible with the Red Book in that Blue Book (data) CDs can be safely used on audio players. The one problem with CD Extra format discs is that its multisession format makes it unusable by first-generation CD-ROM players.CD-I: (CD Interactive) An extension of Yellow book, allowing discs to contain a mix of audio and video, plus data which the user can control interactively. CD-I discs use Mode 2, Form 1 and Mode 2, Form 2 tracks which, like CD-ROM/XA, enable computer data and compressed audio, video, or pictures to be played back at the same time. CD-I tracks cannot be played on normal CD-ROM drives, but specialized CD-I players can play audio CDs, CD+G, Photo CD, and with a CD-V cartridge, Karaoke CD or CD-V discs.CD + MIDI: A type of CD which includes both audio data and MIDI data, i.e., a recording of both the sound of a musical performance, as well as the MIDI data used to generate it. This allows the user to "play with the performance" by choosing different patches, etc. This requires a MIDI Out socket on the CD player.CD-R: See CD.CD Single: A small CD that can record 20 minutes of stereo music; it is 80mm in diameter.CD-V: CD Video. The CD medium modified to record video signals as well as digital stereo audio signals. The video information is recorded in analog form, rather than digital, like a small laser disc.
  • CEDAR
    Computer Enhanced Digital Audio Restoration. A British-developed system for the restoration and preservation of old audio recordings. See also NoNoise.
  • Center detent
     A notched position in the range of a variable control, allowing the user to return the control to precisely that position, such as the midpoint between the left and right channels in a balance control. Use to denote the flat position on tone controls, etc.
  • Center frequency
    The frequency that is boosted or attenuated most by the operation of any parametric equalizer or other similar processing device or circuit. See Q.
  • Center tap
     In a transformer, the electrical midpoint of the windings made accessible for external connection. Used, for example, in delivering power to balanced line condenser microphones. See phantom power, Appendix B.
  • CG
    Abbreviation for Computer graphics.
  • Chain
     Also called iron. An integrated system composed of separate audio and/or video recording, processing, or playback circuits and/or devices which are used in conjunction with one another to produce one output result. See B-chain, program chain, signal chain, side chain.
  • Change-over dots
    See projection.
  • Change-over projection
    See projection.
  • Channel
    An independently processed or recorded signal. (1) An electrical signal path. In analog audio (such as a mixer), each channel consists of separate wired components. In the digital domain, channels may share wiring, kept separate through logical operations. (2) A system for independently addressing up to sixteen separate MIDI devices over a single MIDI cable. MIDI provides definitions for 16 channels which transmit not audio signals, but digital control signals for triggering synthesizers and other devices. MIDI data are associated with a particular channel by virtue of a Channel ID Number that is interwoven with other MIDI data being recorded. A track holds data that (depending on the sequencer) may or may not be restricted to one MIDI channel. MIDI’s 16-channel limitation has been overcome by employing multiple independent MIDI ports that each route sixteen channels, offering the possibility of hundreds of channels. (3) The left or right signals of a stereo audio system, or the left, right, center, surround and/or subwoofer signals of a multichannel system, such as LCRS or 5.1. (4) In film, A complete, self-sufficient recording setup. A production channel would include a recorder, mixer, microphones, headsets, etc. A transfer channel would include a 1/4" tape deck, a 35mm mag recorder, a resolver, and a monitoring system.
  • Channel assignment matrix
     In a recording console, the group of buttons or switches by which the signal from any input channel can be assigned to one or more busses, and thereby be sent to one or more tracks of the multitrack recorder.
  • Channel bit rate
     The actual bits being read from a digital medium are greater than the number strictly required to encode the audio signal. This is because of ECC and synchronization bits, etc. For example, with a CD, the audio bitrate is 1.41Mbps, but the channel bit rate is actually three times as high, 4.32Mbps.
  • Channel insert
     An insertion point in a mixer channel which opens up the signal path and allows an outboard device to be inserted in-line. The output point (the place where the signal is routed to the outboard device) is called the channel insert send, and the place where the effected comes back into the mixer is called the channel insert return. The actual point at which the channel signal path is broken with the insert connection is not standard among all consoles. Some are between the preamp and equalizer sections, some after the equalizer, but before the fader, and some are post-fader. Some are switchable with an internal jumper or other modification. If, for example, the channel insert send is post-fader, the fader setting will affect the action of a compressor that is inserted into the channel’s signal path. On the other hand, a post-fader insert is good when it is desirable to send a single channel’s signal direct to a tape track, making the fader into a convenient record-level control. See normalled connection.
  • Channel message
     A class of MIDI messages which only affect devices on a MIDI network set to a particular channel, i.e., all non-system messages. Channel messages may be of either Channel Mode or Channel Voice type. See MIDI.
  • Channel mode
    See MIDI mode.
  • Channel path
    The record section of the signal chain in a mixer. See also monitor path.
  • Channel pressure
    A type of MIDI channel message that is applied equally to all of the notes on a given channel; the opposite of poly pressure, in which each MIDI note has its own pressure value. Also called aftertouch, channel pressure is generated on keyboard instruments by pressing down on a key or keys while they are resting on the keybed. Also called channel key pressure.
  • Channel separation
     The amount of crosstalk between the channels of a stereo system. It is the inverse of inter-channel crosstalk, as measured in decibels. A small amount of crosstalk is equivalent to a large channel separation.
  • Channel separation
    Channel separation refers to the amount of crosstalk between the channels of a stereo system. It is the inverse of interchannel crosstalk, as measured in decibels. A small amount of crosstalk is equivalent to a large channel separation.
  • Channel strip
    One of multiple identical sections in a mixering console from the mic preamp and phantom power (if present) to the bus outputs, and typically includes the input pad, EQ, and signal routing, including pan, effect sends and effects returns, and main channel fader, and optionally an automation interface. There is one channel strip per mixer input.
  • Channel Voice
    A classification of MIDI channel message relating specifically to a musical performance, where features of the performance (notes, articulation, etc.) are individually described by a unique message. Channel Voice messages include Note On, Note Off, Polyphonic Key Pressure, Channel Pressure, Program Change, Pitch-bend, and Controller Change. These messages all include a specific channel number, allowing similar messages to address different devices on the same MIDI network. The message will only be implemented by a receiving device whose channel number matches that of the message.
  • Channelize
     See MIDI mapping.
  • Characteristic impedance
     See termination.
  • Charge (C)
    A measure of the quantity of electricity and its unit is the coulomb. In an electrical circuit, charge consists of negative charges, or electrons. A positive charge can be thought of as simply an absence, or deficiency of electrons. Charge is what is moving in an electric current. See ampere
  • Chart
     (1) A musical score or arrangement. The term is used both to designate the conductor’s full score, or any band part. (2) A list of current hit singles or albums.
  • Chase
     (1) The process whereby a slave device attempts to sync to a master clock. (2) In MIDI parlance, to chase means, upon playback, to look backward to earlier MIDI events to see if there were any program or channel change messages prior to the playback point which would affect playback. See controller chasing.
  • Chase-lock
    A type of controller for a video or audio recorder that will listen to the SMPTE timecode signal from the master clock device and will adjust its own speed to find the correct time and then will lock into synchronization with the external timecode. Unlike sync-lock, chase-lock controllers respond to changes in timecode sequence.
  • Chasing
     See controller chasing.
  • Chassis ground
    The practice of connecting the signal ground of a device to the rack rails or other common grounding location on a multi-component electronic system.
  • Chatter
    When the input signal level to a noise gate hovers near the threshold level, the gate may be unsure if it should be open or closed. It may rapidly open and close, resulting in the audio cutting in and out; this is known as the gate "chattering." To correct this problem, adjust the threshold setting to be slightly lower or higher.
  • Checksum
    A number derived from arithmetical actions on data, used to check that data has not been corrupted after transmission or recording and replay.
  • Chip
    (1) In vinyl record production, the thin thread of acetate lacquer that is carved out of the master disc by the cutting stylus. Also called swarf. (2) A slang term for integrated circuit.
  • Chirping
    An effect caused by the overuse of single-ended noise reduction systems whereby the low-level signals take on an electronic, "ringing" character, known as chirping. If the signal is very noisy, the noise floor itself begins to sound chirpy, which can be more annoying than the original, broad-spectrum, noise.
  • Chord
    The playing of multiple notes simultaneously. The opposite of an arpeggio. See inversion.
  • Chorus
    (1) A regularly repeated section of a song or other musical composition. (2) A group of singers, also called a choir.
  • Chorusing
    A type of audio effect in which a delayed (30-40ms) or detuned copy of a signal is mixed with the original signal. The mixing process changes the relative strengths and phase relationships of the overtones to create a more complex sound. See ADT, double-tracking. The mixture becomes extremely complex as the relative phases of the signals cause partial cancellation and reinforcement over a broad frequency spectrum. The simplest way to achieve chorusing is to detune one synthesizer oscillator from another to produce a slow beating between them. See comb filter.
  • Chromatic
    Pertaining to the full twelve-note scale, as opposed to the eight-note diatonic scale.
  • Cinema Digital Sound (CDS)
     A new system of digitally recording motion picture sound format introduced by the Optical Radiation Corporation, a division of Kodak, in 1990, for the film "Dick Tracy" for digital sound on 35mm or 70mm film formats via a laser beam, which reportedly combines the dynamic and frequency ranges and low distortion of the CD on six discrete channels. Five channels encompass the full audio bandwidth and the sixth is designated a subwoofer channel, containing only the lowest frequencies. The CDS-encoded film is capable of being shown with conventional stereo optical sound, but requires a special sound system to reproduce the six channels digitally. First used in 1990, this format lasted only two years and is now obsolete. See AC-3, 5.1.
  • CinemaScope
    The trademark of a widescreen camera system developed by Twentieth Century Fox, the first true stereophonic motion picture sound system which had the sound tracks on the same film with the picture. First used in 1953, CinemaScope was responsible for popularizing the anamorphic film format.
  • Cinerama
    A widescreen system comprising three 35mm cameras/projectors running in interlock with 7-track mag film.
  • Cinerama
    A widescreen system comprising three 35mm cameras/projectors running in interlock with 7-track mag film
  • CIRC
    Cross Interleaving Reed-Solomon Code. The combined error detection and correction scheme used in CDs. See interleaving.
  • Circle of Fifths
     Also known as the Cycle of Fifths. A way of thinking of the twelve major and minor keys as a circle, arranged in steps of a fifth, which can be read in either direction. Starting from Cmaj and proceeding clockwise, the key signature of each new key gains one sharp until Fmaj is reached. At that point, FA becomes GBmaj and the cycle continues, removing a flat at each step until back to C. If one goes counter-clockwise, the circle is a series of perfect cadences, with each new tonic key becoming the dominant of the next. For this reason, the Circle of Fifths is often used for modulation, especially to or back from a remote key, i.e., a key on the far side of the circle.
  • Circle of Fifths
    A way of thinking of the twelve major and minor keys as a circle, arranged in steps of a fifth, which can be read in either direction. Starting from Cmaj and proceeding clockwise, the key signature of each new key gains one sharp until Fmaj is reached. At that point, FA becomes GBmaj and the cycle continues, removing a flat at each step until back to C. If one goes counter-clockwise, the circle is a series of perfect cadences, with each new tonic key becoming the dominant of the next. For this reason, the Circle of Fifths is often used for modulation, especially to or back from a remote key, i.e., a key on the far side of the circle.
  • Circuit
    A complete path that allows electrical current from one terminal of a voltage source to the other terminal.
  • Circumaural
    A headset with a large cushion which surrounds the ear to exclude external noise, unlike supra-aural or intra-aural designs.
  • CIT
     See SDMI.
  • Clangorous
    Meaning containing partials that are not part of the natural harmonic series, i.e., partials which are not whole-number multiples of the fundamental frequency. Clangorous tones often sound bell-like.
  • Clef
     In written music, a symbol placed at the beginning of the stave which assigns a pitch to a specific line on the stave, and by inference, to all of the other lines and spaces. Three clef symbols are commonly used, derived from the medieval forms of the letters G (&), F(?), and C(B).
  • Click track
    A click track records a series of clicks, like a metronome, on one channel of a multitrack tape recorder or one channel on a MIDI sequencer. The click track is used to synchronize the recording of subsequent tracks by playing it back via headphones to the musicians while they are overdubbing the added tracks.
  • Clipping
    A distortion caused by cutting off the peaks of audio signals. Clipping usually occurs in an amplifier when its input signal is too high or when the volume control is turned up too high. A clipped waveform contains a great deal of harmonic distortion and sounds very rough and harsh. Hard clipping results in very sharp edges on the waveform, producing the maximum amount of high-harmonic content. Soft clipping produces rounded edges of the clipped waveform and is much less grating on the ears and tweeters than hard clipping as it contains much less very high-frequency energy. Different amplifiers produce different clipping effects; tube amps often produce soft clipping. See full code, digital black.
  • Clock
     (1) Any of several types of timing control devices, or the periodic signals that they generate. Clock pulses are usually derived from crystal-controlled oscillators. See also MIDI Clock, master clock. (2) In recording sessions for jingles or film scores, a stopwatch.
  • Clock noise
    An artifact of digital-to-analog conversion that creates staircase-like changes in voltage produced by the converter. Most clock noise is caused by shifts in the zero-crossing times. See quantization noise, reconstruction filter.
  • Clock reference
    See master clock.
  • Clock resolution
    The precision (measured in ppq) with which a sequencer can encode time-based information. A sequencer’s internal clock is always set to some ppq value, and this setting is one of the main factors that determine how precisely the sequencer can record time-dependent information. The actual clock speed is usually determined by the bpm setting. See MIDI clock.
  • Closed-loop
     A closed-loop system is one that modifies its behavior based on the different behavior between an output variable and a set point, i.e., it relies on feedback to determine its output. The opposite of an open-loop, an example of a closed-loop system is a household thermostat. In audio, the main use for closed-loop systems is in power amplifier output stages. See bootstrap.
  • Cloth track
    See Foley.
  • CLV
     Constant Linear Velocity. As opposed to CAV, a mass storage system that has a disk whose speed varies to keep the data rate at the read/write head constant, regardless of the location of the data on the disk. The CD standard specifies CLV format.
  • CMRR
    Common Mode Rejection Ratio. In a balanced line connection, the common mode is the noise whose phase is common on both lines. The degree of attenuation of the common mode by a differential amplifier is called the rejection ratio, and like other level-modulating devices, the output change is measured in dB.
  • Coaxial
    Speakers that have two separate drive units (normally a small woofer and tweeter) moving independently. Essentially this gives better high frequency response and hence greater range and clarity.
  • Cocktail party effect
    The phenomenon of human aural discrimination among sounds of equal loudness, e.g., the ability to hear one conversation out of many at a party. Related to auditory masking.
  • Coda
    Musical symbol (C) which references a section of music which is to be repeated from or repeated to, as in "D.C. al Coda," meaning "play from the beginning to the Coda." A coda is a musical passage that gives a sense of completion to a movement or work, possibly an extended cadence or a substantial passage. A codetta is a short musical passage that links the subject and answer in a fugue, or at the end of the first passage of a sonata.
  • Code window
    A display of the SMPTE timecode numbers, usually corresponding to each frame of picture viewed on a monitor. These numbers appear in a window that replaces a portion of the program image, usually at the bottom right of the screen. Depending on the equipment used, the timecode data in the window can be either generated in real-time from the source of the SMPTE timecode data, or have been recorded as a permanent part of the picture on a particular copy of a pre-recorded program. BITC is generally recorded onto copies of footage that will be used for off-line editing. The source of the SMPTE timecode data in this latter case is the sync track or control track of the original video footage.
  • Codec
    COder-DECoder. A device that digitizes an input waveform, eliminating redundant information, reducing the number of bits needed to carry the same data, then decoding the data at the receiving end, hopefully with a high degree of sonic transparency. See PCM, PWM.
  • Coding
    The process of altering the form of a signal, such as from analog to digital. Or, the coding may be used to allow a transformation of the signal not possible in its original form such as in noise reduction. Or, coding may be used to take advantage of effects inherent in the coding process itself, such as in PCM which allows recording and playback with low noise. The complementary stage to coding is decoding, a process which attempts to reconstruct the original signal, i.e., from digital back to analog for use with loudspeakers. See codec.
  • Coercivity
    The magnetic field strength required to bring any specific type of recording tape, when fully saturated, to complete erasure. Measured in Oersteds, and abbreviated
  • Coherence
    The polarity relationship between two complex sounds or signals being combined, measured at any instant. Total phase coherence indicates complete phase alignment or full signal reinforcement. Incoherence, to any degree, designates a partial to complete phase difference, producing partial to total phase cancellation. The opposite of incoherent. See also isochronous
  • Coincident pair
    Also known as an X-Y or XY pair, this is a microphone configuration which commonly uses two cardioid or figure-eight microphones mounted at right angles to one another, the latter preferred only for special applications. This is called a coincident pair because the two microphones are mounted as closely as possible to each other so that the sound being captured arrives at both microphones at exactly the same time, regardless of the direction of the source. All coincident configurations have to use directional microphones in order to create the necessary level differences between the two channels of the stereo system; omnidirectional microphones do not produce level differences proportional to the angle of incident sound. This technique is favored by many broadcast applications because of good mono compatibility. Recording with a coincident pair is called XY recording in the US and the UK, AB recording throughout Europe, and also crossed pairs, or normal stereo. In the US, "AB recording" means a spaced pair. See also Blumlein pair, near-coincident pair. Contrast with spaced pair.
  • Color burst
    An analog video, composite video signal generated by a video-signal generator used to keep the chrominance subcarrier synchronized in a color television signal.  See videoblack.
  • Coloration
    Subtle distortion which results in a change in the timbre of a sound without that sound being otherwise noticeably distorted, such as a smearing type of distortion produced by intermodulation distortion. More prevalent at high audio frequencies.
  • Comb filter
    A type of notch filter that produces a series of very deep notches, or dips, in its frequency response. The spacing of the notches along the frequency axis is at multiples of the lowest frequency notch. A comb filter is produced when a signal is time-delayed and added to itself. Frequencies where the time delay is one-half the period and multiples of these frequencies are cancelled when the signals are combined because they have opposite polarity, usually used to filter out 60Hz hum and its associated harmonics. If the signals are of equal strength, the cancellation is perfect and the notches are infinitely deep on a decibel scale. See common mode. Also called timbral interference cues.
  • Combining amplifier
    An amplifier, also called a summing amplifier, combines two or more signals prior to sending them to a single audio bus, signal processor, tape recorder track, or other destination. For example, on a mixer, if an aux send controls on all channels of a console feed a combining amplifier, whose output can be routed to a reverb system, cue or headphone amp, the monitor amplifier, etc. There are also devices which are active combining amplifiers, called an ACA, as well as passive combining networks
  • Combining network
     A typically passive network in which two or more signals are combined before being sent to a single bus, signal processor, or other destination.
  • Combo
    A combination of loudspeaker(s) and amplifier in one unit, usually portable. Used by guitarists, keyboard players, etc. for stage amplification.
  • Comma of Pythagoras
    See diatonic comma.
  • Commag
    A technical term for composite magnetic print.
  • Common mode
     Referring to equal voltages induced in the two wires of a signal-carrying pair. In a balanced line circuit, the signal voltages are of opposite polarity in the two signal wires. Any voltage which appears with the same polarity on each wire is called a common-mode voltage. Usually noise, such as a 60Hz hum, is induced in audio cables equally and in the same direction, and so is a common-mode voltage. If the signal is connected to a differential amplifier input, the common-mode voltages will cancel, while the signal voltages, being of opposite polarity on each input terminal, will add together. This is the reason why balanced lines are less prone to induced noise from external influences. See CMRR.
  • Common mode rejection
    The measurement of how well a balanced circuit rejects a common mode signal. See also CMRR
  • Comopt
    A technical term for composite optical print.
  • Compander
     Short for compressor/expander. A compander is a device for noise reduction in audio devices such as tape recorders. The compander will reduce the dynamic range of the signal before sending it to be recorded. The compression makes the softer passages louder so the dynamic range recorded on the tape is less than it would be if it were not compressed. Then, on playback of the tape, the signal is expanded; that is, the softer passages, which are too loud on the tape, are reduced in volume to match the original signal, restoring its dynamics. In the expansion, which is similar to a fast-acting AVC, the noise introduced by the tape recording process is effectively reduced because the music, when loud, masks the noise, and during the soft passages, the volume is turned down, making the noise comparatively softer. Digital companding allows a device to achieve greater apparent dynamic range with a lower bit depth. See dbxSeedBx, Dolby noise reduction.
  • Companding converter
    An A/D-D/A pair which uses a non-linear scale, i.e., one that has larger steps towards peak amplitude and smaller steps towards minimum amplitude. This scale increases the ability of the converter to resolve small changes in low amplitude signals, reducing distortion, but with the penalty of increased noise. The overall effect is that of a compressed analog input signal and a resulting expanded digital output. See compander.
  • Companding Noise Reduction
    Companding noise reduction works by first sending the source matrial through a compressor, thus compressing the source material's dynamic range (in this case by a factor of 2) before being recorded to a medium known for noise such as magnetic recording tape. The compressed audio becomes contaminated with noise, but is passed through an expander during playback, and the noise from the recording medium is masked by expansion of the dynamics. This results in a reduction of perceived noise. See also dbx™ noise reduction.
  • Compatibility
     (1) The degree to which different pieces of equipment can be used together or are interchangeable, e.g., whether a tape recorded with one type of NR can be replayed on a tape player equipped with another type of NR. (2) See mono compatibility.
  • Complementary
    Any pair of audio signal processing procedures which perform two equal and opposite processes on the signal, one before recording, the other after playback. Noise reduction and tape recorder pre- and post-emphasis are examples. See encoding.
  • Completely filled
    See 4-track.
  • Composite equalization
     The overall frequency response modification produced when a signal passes through more than one equalizing circuit in the same device, or through several equalizers in a series.
  • Composite print
    Film print that contains a sountrack.
  • Compound time
    See time signature.
  • Compression
    (1) The process of reducing the dynamic range of an audio signal by reducing the peaks so as to be able to boost the low levels. For every dB of compression applied, the S/N ratio is worsened by 1dB, assuming that the make-up gain is set so that the maximum levels of the compressed and uncompressed signals are the same, as the quieter parts of the original signal, plus any noise contained in these regions, will be raised in level. (2) A dynamic-range problem in loudspeakers caused by nonlinearity under conditions of high input power levels. At very high levels, the acoustic output increases more slowly or ceases to increase altogether as the input power increases, producing nonlinear distortion, i.e., a frequency response curve very different for very high levels. (3) Data compression used on digital audio files is a process ADPCM, MACE, for example. (4) The opposite of rarefaction whereby a quantity of data is reduced in order to occupy less storage space. See ATRAC.
  • Compression driver
    A specialized mid- or high-frequency speaker consisting of a small diaphragm and voice coil coupled to a large magnet structure. The unit is mounted to a horn which acoustically matches the impedance of the driver to the impedance of the air and shapes the signal. Expensive due to the precise tolerances required, compression drivers are substantially more efficient than traditional direct-radiating cone speakers.
  • Compression ratio
     (1) The ratio of the dB change from input level to output level effected by a compressor, once the threshold has been exceeded. (2) In data compression, the ratio of the number of bytes of uncompressed to compressed data, an indication of the space-saving efficiency of the compression algorithm.
  • Compressor
    A device for reducing the effective dynamic range of an input signal by preventing it from rapidly exceeding or falling below a selected amplitude threshold. The first part of a compander, it is used to make loud parts of a signal softer and soft parts louder. Beyond the threshold, the ratio of the signal’s input level to its output level (e.g., 2:1, 4:1) is user-selectable. A compressor is commonly used to keep mic levels within an acceptable range, but because it can slow a signal’s rate of decay below the threshold, compressors are also used to add sustain to instruments such as electric guitar and bass. The limiter acts like a compressor, but operates only at the top end of the dynamic range. The limiter has a faster attack time (1µs to 1ms) than the compressor alone (1ms to 10ms). A compressor/limiter is inserted between the outputs of a MIDI soundcard, synthesizer, or mixer and the inputs of the mixdown deck. See hard knee compression, soft knee compression, Limiter
  • Comtek
     (1) A Salt Lake City-based company that makes portable wireless transmitters and receivers. (2) The generic name for wireless headphone feeds to directors and for wireless timecode feeds to slates.
  • Concert pitch
    Established by ISO in 1955, the agreed reference frequency of 440Hz, for the note A above middle-C, notated A=440
  • Concert pitch
    Established by ISO in 1955, the agreed reference frequency of 440Hz, for the note A above middle-C, notated A=440.
  • Condenser microphone
    A condenser, or capacitor, mic capsule has a conductive diaphragm and a metal backplate placed very close to the diaphragm. They are charged with static electricity to form two plates of a capacitor. When sound waves strike the diaphragm, it vibrates, varying the spacing between the plates. In turn, this varies the capacitance and makes a signal analogous to the incoming sound waves. There are two types of condenser mics: the true condenser and the electret condenser. In the former, the diaphragm and backplate are charged with a voltage from a circuit. In the latter, the diaphragm and backplate are charged by an electret material, which is in the diaphragm or on the backplate. All true condenser mics need a power supply to operate, such as a battery or phantom power. In general, condensers have a smooth, detailed sound with a wide, flat frequency response--usually up to 15kHz-20kHz, useful for cymbals or instruments that need a detailed sound, such as acoustic guitar, strings, piano, or voice. Condenser mics tend to be more expensive and fragile than dynamic microphones. Note that omnidirectional condenser mics have deeper lows than cardioid condensers, making the former a good choice for pipe organs and bass drum. See also boundary microphone.
  • Conductance
    The reciprocal of resistance, or electric current divided by voltage. The traditional unit of conductance is the mho (ohm spelled backwards). See also impedance.
  • Conductivity
    A material which exhibits efficient thermal or electrical transference through itself is said to have a high conductivity. Conductivity in a material is rated as its resistivity, the inverse of conductivity, in ohms per meter. Metals have a high conductivity owing to the large number of free electrons in metal atoms which efficiently transfer the current or heat from one part of the material to another. An insulator, on the other hand, is a material with few free electrons, and hence does not readily pass heat or current.
  • cone
     The vibrating diaphragm of a dynamic or moving coil loudspeaker, usually made of paper and shaped roughly like a cone.
  • Conform
    (1) To re-edit sound stems to match a new version of the picture edit, which is the final matching of all music, dialog and/or special effects to the video image. This may involve synchronization, editing, and re-recording one or more of the components of the final sound/video mix. (2) To assemble sound elements from their original sources to match their location in a picture edit, often with the assistance of an EDL.
  • Console
    See mixer.
  • Consonant
     Literally "sounding together." Musical tones that are consonant sound harmonious or in tune when sounded together rather than discordant or harsh. Musical intervals composed of tones that have relatively simple frequency ratios are more consonant than ones with more complex ratios. The most consonant interval is considered to be the octave, which has a frequency ratio of 2:1.
  • Contact
    See wrap.
  • Contact enhancer
     A chemical compound which, when applied to plugs, sockets, or other metallic electrical connection, improves the electrical conductivity between the metal surfaces, making a better, less noisy contact.
  • Contact microphone
    A mic that is physically attached to the body of an instrument or other sound source. It is primarily the vibration of the contact microphone’s body itself that is the transducer. By comparison, other microphones contain an internal diaphragm or membrane that vibrates in response to sound carried to it through the air, while the capsule of the microphone itself remains motionless. See also bug, piezo pick-up.
  • Contact Pickups
    Convert sound waves in a dense medium (wood, metal, skin) into an audio signal. Sometimes used on acoustic stringed instruments such as guitar, mandolin, violin, etc. Usually of the crystal type, occasionally capacitive.
  • Container
    Film sound slang for Dolby Laboratories’ peak limiter designed specifically for controlling the dynamics of program material during SVA printmastering.
  • Continue
    A MIDI Real-Time system message, correctly written Song Continue.
  • Continuous controller
     A type of MIDI channel message that allows dynamic, real-time control changes to be made in notes that are currently sounding. There are 128 possible continuous controllers on each of 16 MIDI channels, and each of these controller types can have any data value between 0 and 127. Modulation (such as pan or volume) is an example of a true MIDI continuous controller. Continuous controller 1 is always the modulation wheel; controller 7 is the instrument’s main volume. See controller.
  • Continuous sync
     A software feature where the DAW will create a new clock based on incoming SMPTE timecodetime code to enable recording to the DAW from an ATR. The result is that the sample rate of the DAW will vary continuously, effectively speeding up and slowing down to track the timecodetime code variations. Continuous sync requires dedicated hardware, and may not be available on all DAWS. For example, ProTools™ has a feature for continuous sync which is necessary when syncing continuously to an ATR while recording on any digital machine as the SMPTE timecodetime code-based clock is not guaranteed to be at the precise sampling rate. The ProTools Slave Driver™ does the sample rate conversion in the ProTools hardware so that the audio quality of the digital data isn’t compromised.
  • Contour generator
    See envelope generator.
  • Control and Display signals
    Also called PQ codes. In the CD format, eight additional bits are added to each frame of audio data; this means that a byte of information is available from the disc every 136 µs. Each bit in the added byte is given a one-letter name, P-W. Thus, eight separate subcodes can be recorded on and recovered from the CD. So far only P and Q are used: the P-code is used for the pause signal between musical tracks and at the end of the last track, and the Q-code tells the player if the recording is two- or four-channel (no quadraphonic CD player is yet available). The Q-code also contains timing information about the tracks and identifies the country of origin and date of the recording. No standard has been defined for the use of the other six subcodes.
  • Control module
    The part of a synthesizer that tells the sound generators and controllers what to do to make a given note. These modules include envelope generators, LFOs, the keyboard itself, and the modulation and pitch-bend wheels. These allow control of some aspects of a synthesizer’s sound by sending signals to the sound generators and modifiers telling them now to behave. For instance, the keyboard sends a signal to the oscillator telling it what frequency to play. Also called modulation modules.
  • Control panel
    A file which becomes a part of the Mac’s system software, giving the user either control over or adding functionality to various aspects of the operating system, peripherals, or applications. See also extension.
  • Control track
     (1) One track of a multitrack magnetic tape recorder used for recording special signals that provide control information to the recording console during automated mixdown. (2) A dedicated track prerecorded with a pilot tone, used on video tape which marks the start of each video frame in order to resolve playback speed by controlling and synchronizing the video frames. Can be used to count time for editing, but is prone to slip and lose count during winding. In 1" and " formats, SMPTE timecode information is sent to a separate address track which creates confusion about the names of both of the tracks. See blacking, sync-locksync lock.
  • Control voltage
     A voltage, usually varying, used in synthesizers to control various parameters of the signal being produced. Control voltages are used for envelope control, pitch control, and filter bandpass and rolloff frequency control, etc. Suitable control voltages can be generated in various ways, one of the most straightforward of which is by a standard keyboard. See VCA, VCF, VCO.
  • Controller
    (1) Any device, for example, a keyboard, wind synth controller, or pitch-bend lever, capable of modulating a sound by altering the action of some other device. (2) Any of the defined MIDI data types used for controlling the on-going quality of a sustaining tone via a controller message. In many synthesizers, the controller data category is more loosely defined to include pitch-bend and aftertouch data. See continuous controller.
  • Controller change
    A Channel Voice message which allows for musical effects such as vibrato or sustain on currently active voices.
  • Controller chasing
    A sequencer feature whereby whenever playback is requested, the sequencer looks back for the most recent controller, pitch-bend, aftertouch, and similar parameters and sets everything accordingly so that playback started in the middle of a song replays correctly.
  • Controller chasing
     A sequencer feature whereby whenever playback is requested, the sequencer looks back for the most recent controller, pitch-bend, aftertouch, and similar parameters and sets everything accordingly so that playback started in the middle of a song replays correctly.
  • Convolution
     (1) In any linear system or device, the output signal is a function of the input signal and the characteristics of the device. The interaction between the input and the device is described by a mathematical infinite integral called convolution. The output is the input convolved with the impulse response of the device. The spectrum of the output of a device is simply the spectrum of the input multiplied by the frequency response of the device via the FFT. (2) The modulation of one audio file by another. For example, the use of a hand-clap echo sample could be convolved with a guitar chord sample to produce an echo effect which sounds like it was produced by the guitar.
  • Copy editing
    The process of re-recording or copying selected extracts from original sound or video recordings and rearranging their order as they are copied, so that the copy will have all the desired segments in the correct order. This copy is called an assembly, and will generally need fine editing in order to meet timing or other production requirements.
  • Corner frequency
    See rolloff frequency.
  • Correlated noise
    See distortion.
  • Cosine microphone
    See figure-eight microphone.
  • Cottage loaf microphone
    UK slang for cardioid microphone. See supercardioid or hypercardioid microphone.
  • Coulomb
    The coulomb is the unit of electric charge (C), and is the quantity of electricity transferred in one second by a current of one ampere.
  • Counts
    A slang term for footage numbers or cues for specific events in a film or videotape. Also called footage counts. See feet/frames.
  • Coupling
    The process of or means by which energy is transferred from one system or medium to another. For example, the coupling of acoustic energy from a loudspeaker to the surrounding air.
  • Cps
     (1) centimeters per second. The speed of movement of tape past a tape read/record head, also denominated in ips, inches per second. (2) cycles per second, or Hertz.
  • CPU
     Central Processing Unit. The brain of the PC. Its clock speed determines how many software plug-in effects and soft synth notes can be run simultaneously in real time. The two most popular manufacturers of CPUs are AMD and Intel.
  • CPU Fan
    The CPU generates a significant amount of heat when it’s running, so to ensure that it doesn’t overheat its normally fitted with a finned metal heat sink to help dissipate the heat, and some sort of fan that generally blows cool air onto the heat sink. The standard fans can be quite noisy, which is not good in a recording studio. To keep down the noise you can purchase a replacement fan that is not as noisy.
  • CRC
     Cyclic Redundancy Check. A system of recording a checksum number along with data in order to detect, and in some cases, correct any corruption of the data. See ECC.
  • Crescendo
     A gradual increase in loudness of a musical sound.
  • Crest factor
    The ratio between the average amplitude as shown on a VU meter and the instantaneous amplitude as shown on a peak meter. The human ear is very sensitive to this difference.
  • Critical distance
    The distance from a loudspeaker where the direct sound is equal in intensity to the reverberant sound. See also free-field.
  • Cross-fade
    A velocity threshold effect in a synthesizer in which one sound is triggered at low velocities and another at high velocities, with a fade-out/fade-in transition between the two. If the transition is abrupt rather than gradual, the effect is called cross-switching rather than cross-fading. Cross-fading can also be initiated from a footswitch, LFO, or some other controller.
  • Cross-fade looping
    A sample-editing feature found in many samplers and most sample-editing software, in which some portion of the data at the beginning of a loop is mixed with some portion of the data at the end of the same loop, so as to produce a smoother transition between the end of the loop and the beginning of the loop replay.
  • Cross-interleaving
    See interleaving.
  • Cross-mod
    Cross-modulation test. A means of determining correct exposure on a track negative to result in minimum distortion on a positive print. Tests are conducted to determine the relationship of specific optical cameras to specific laboratories.
  • Cross-switching
    A velocity threshold effect in a synthesizer in which one sound is triggered at low velocities and another at high velocities, with an abrupt transition between the two. If the transition is smooth rather than abrupt, the effect is called cross-fading rather than cross-switching. Cross-switching can also be initiated from a footswitch, LFO, or some other controller. Also called velocity-switching.
  • Cross-switching
    A velocity threshold effect in a synthesizer in which one sound is triggered at low velocities and another at high velocities, with an abrupt transition between the two. If the transition is smooth rather than abrupt, the effect is called cross-fading rather than cross-switching. Cross-switching can also be initiated from a footswitch, LFO, or some other controller. Also called velocity-switching.
  • Crossed pairs
    See coincident pair.
  • Crossover distortion
     A type of distortion present in some amplifiers which increases for low-level signals. In many amplifiers, the output devices are connected so that one of them is active during the positive half of the waveform, an the other one is active for the negative half. There is a region near zero current where the signal is transferred from one to the other. If this is not done smoothly, there will result a small discontinuity in the output waveform. This discontinuity causes higher-order harmonic distortion, and being constant in value, is more noticeable with low-level signals than with stronger ones. See crossover frequency.
  • Crossover frequency
    The frequency above and below which an audio signal is divided into two bands, each of which is directed to a separate destination. Precisely, the frequency at which each of the two bands is attenuated 3dB by the crossover network.
  • Crossover network
    A dividing network that splits a full-spectrum signal into two or more frequency bands and routes them to feed the various components of a speaker system. Passive crossover is a speaker design whereby multiple speakers are in a single enclosure and sound frequencies are separated and sent to be driven by the appropriate speaker. A two-way biamp monitoring system has a high-frequency loudspeaker (tweeter) and a low-frequency speaker (woofer). A three-way triamp system has a third speaker to reproduce midrange frequencies. Active crossovers divide a line-level output signal from a mixer or other sound source and route the resulting signals to individual amplifiers optimized for the different speaker components.
  • Crosstalk
    In multichannel audio transmission systems, such as tape recorders, record players, or telephone lines, a signal leaking from one channel to one or more of the others is called crosstalk. Also known as bleeding. See channel separation.
  • Crystal sync
    A system for generating a sync signal that will ensure proper synchronization of film footage and its corresponding sync sound without using any sync reference, such as 60Hz AC line frequency. Two piezoelectric crystals, each tuned to the same high frequency, are installed in the camera and recorder. The crystal in the camera precisely controls the motor speed during shooting. The crystal in the recorder produces a pilot tone that is recorded on tape in the same way which the camera motor speed would be recorded through the conventional sync cable. Because the two crystals are tuned identically, the dailies, when synched with the magnetic film copy of the original sound takes, will maintain perfect sync once the slate marks are aligned. Crystal sync generators are also installed in portable video cameras and VTRs. See Nagra, neo-pilot.
  • CT
    Clock time. See RDS.
  • Cue
     (1) (noun) A piece of music for a specific scene or event in a film. A specific part of a film soundtrack which correlates to a visual event in the film is called a cue point or hit point. (2) (verb) To position a sound source to activate at a specific time. See Real-Time MTC Cueing. spot.
  • Cue box
    A wall-mounted or movable box that receives one or more monitor mixes from the recording console, and that has jacks to plug in several sets of headphones used to send the cue mix to singers or instrumentalists in overdubbing, a narrator, or other studio talent. Also called a headphone box. See cue system.
  • Cue line
    A line drawn on the workprint, meant to be seen during projection in post-dubbing or scoring, which gives the actor or conductor a visual cue to begin.
  • Cue list/sheet
     A list of the footages and frames, beginning with 00:00, at which specific shots begin and end. Used by the re-recording mixer who needs to know which sounds or music must be played as the final mix proceeds. See also edit decision list, feet/frames.
  • Cue mix
    The blend of live inputs and/or previously recorded tracks sent by the mixing engineer to the headphones of performers playing or singing in the studio. Also called the headphone mix.
  • Cue mode
    A tape machine operating mode in which the tape lifters are defeated while the playback electronics remain operative. Used most often during editing, thus also called edit mode.
  • Cue point
    See Real-Time MTC Cueing.
  • Cue sheet
     A track sheet for mixing that gives locations of edited sounds on a track-by-track bases, either in film footages or in timecode numbers. See binky.
  • Cue system
    The entire electronic circuitry contained within the recording console that allows the engineer to adjustably feed sound from any input module to the cue mix, then out to the musicians’ or singers’ headphones via the cue amp and cue boxes.
  • Cue system
    The entire electronic circuitry contained within the recording console that allows the engineer to adjustably feed sound from any input module to the cue mix, then out to the musicians’ or singers’ headphones via the cue amp and cue boxes.
  • Cue system
    The entire electronic circuitry contained within the recording console that allows the engineer to adjustably feed sound from any input module to the cue mix, then out to the musicians’ or singers’ headphones via the cue amp and cue boxes.
  • Cue track
    A track of recorded music and/or clicks which are sent over headphones to the musicians and/or singers to assist them in overdubbing additional music/vocals. If the track is simply tempo clicks, it is known as a click track.
  • Cue-up
    To locate a desired point, at which a specific sound event happens on a reel of tape, and to position that point just ahead of the playback head on a tape recorder. When playback begins, the desired sound will be heard immediately.
  • Current (I)
     The flow of electrical charge measured in amperes.
  • Cut
    (1) (verb) To attenuate amplitude of a signal or particular frequency band; the opposite of boost. (2) To produce the master for a vinyl LP. (3) In film, the instruction used to terminate filming. (4) (noun) A musical selection on a record, tape, or CD, or a particular edited version of film.
  • Cut-and-paste
    On a hard-disk audio editing system, a term used to denote the ability of an audio editing program to move and/or copy sections of the recorded audio to a new location in the track or to other tracks.
  • Cut effects
     Sound effects that are taken from a sound library and edited, usually as opposed to recorded Foley effects. See pull, M&E.
  • Cut switch
    A switch or button that mutes an audio signal on a mixer.
  • Cut track
    An edited track of a film soundtrack which is ready to be used either as a track in a premix (music or effects), or as a (dialog) track in the final mix.
  • Cutoff frequency
     See rolloff frequency.
  • Cutter
     Sound editor.
  • D.C.
    Da Capo. Italian for "Head," meaning "Play from the beginning."
  • D-connector
    See D-sub(miniature) connector.
  • D.S.
     Dal Signo. "Play from the sign(D).
  • D-sub (miniature) connector
    Also called a D-connector, or a D-type connector. A type of connector commonly found on computers and data transmission devices, including SCSI devices and computer monitors. D-type connectors have a "D-shaped" angled housing, and have 9-pin, 15-pin, and 25-pin configurations, designated DE-9, DA-15, and DB-25, respectively.
  • D-type (connector)
     See D-sub(miniature) connector.
  • DAE
    (1) Digidesign Audio Engine.™ A Macintosh application that can run behind other applications, such as sequencers or ProTools,™ handling the transfer of audio data to/from the hard disk. DAE is licensed by many sequencer developers to avoid writing their own low-level I/O code. (2) Digital Audio Extraction. The process of capturing CD-Audio tracks digitally from a CD-ROM drive to hard drive, using software such as Astarte’s CD Copy™ or OMI’s Disc-to-Disk.™
  • Dailies
     Uncut footage shot each day during production. If picture editing is on film, with picture and synchronized magnetic film, those elements when edited together become the workprint and worktrack. Used to chart the progress of the film and for preliminary music cuts. Also called rushes.
  • Damping
     (1) Damping is the addition of friction to a resonance in order to remove energy from a mechanical system, reducing the magnitude of vibration at resonant frequencies. For example, the reduction of movement of a speaker cone, due either to the electromechanical characteristics of the speaker driver and suspension, or the effects of pressure inside a speaker enclosure. The electrical analog of friction is resistance, and it is used to damp resonating electrical circuits, such as crossover networks and filters. See also Q. (2) Acoustic fiberglass material used inside speaker enclosures.
  • Damping factor
     (1) A factor defined as the rated load divided by the amplifier output impedance. (2) The ability of an amplifier to control the motion of a loudspeaker cone after a signal disappears, i.e., its ability to defeat the natural ringing tendency of the body (cone) in motion. An amplifier with a high damping factor looks more like a kind of short circuit to the speaker, reducing its vibration when the signal stops. The damping factor of an amplifier will vary with frequency, and sometimes a manufacturer will publish a curve of damping factor vs. frequency. The effect of high damping factors is most audible at low frequencies, where the primary resonance of the woofer cone, called hangover, is reduced in level.
  • DAR
    See Digital Audio Recorder. Any type of audio recording system which records upon a digital medium, such as DAT or hard disk. DAT or DCC recorders, digital dubbers, digital multitracks, and hard-disk recording systems are all example of digital audio recorders. These recorders are an alternative to analog recorders, such as traditional cassette or reel-to-reel formats which do not convert the waveform to a digital representation prior to writing it to the recording medium.
  • Darkness
    The amount of low-frequency, or corresponding lack of high-frequency, components of a sound. Reverberation from distant objects usually has fewer high frequencies and sounds darker than reverb from close objects. The opposite of brightness.
  • DASH
     Digital Audio Stationary Head. A standard format for ensuring compatibility between Sony PCM-model digital multitrack recorders which that use stationary, rather than rotating heads. Originally, the DASH format was designed to support 2-track, 8-track, 16-track, and 24-track recorders using reel-to-reel tape. The 8-track and 16-track machines were never marketed, and a 2-track model is no longer in production. The DASH specification now includes double-density, thin-film heads that allow 48-track recording on the same tape originally used by the 24-track devices. DASH-format machines are backward compatible: 24-track machines can be used with newer models, and a project can be started on a 24-track machine and completed on a 48-track recorder, if needed, as the data from tracks 25-48 are written into the spacing between the original 24 tracks. DASH tapes run 30ips at up to 48kHz, with 44.1kHz and other sampling rates supported. In addition to 24-track or 48-track recording, DASH format provides two analog cue tracks and one track each for control and timecode signals. The format covers a wide range of versions, such as from 2-48 tracks and tape speeds from 12-76cps, and was agreed on by Sony and Studer, among others. DASH format recorders are currently manufactured by Sony and Studer. See also S-DAT, ProDigital.
  • DAT
     Digital Audio Tape. There are two formats: R-DAT which uses a rotating head assembly similar to a VCR, records diagonally across the tape, and includes a four-channel format which would permit recording of ambisonics; and the S-DAT which uses a stationary head and records several linear, parallel tracks of digital signals. There are no known commercial S-DAT products. The DAT standard format specifies a small cassette that provides up to two hours of 16-bit, linear, sequential monaural, PCM digital recording at a sampling rate of 32kHz, 44.1kHz, or 48kHz. Also called a DCAC, Digital Compact Audio Cassette. See also Digital Compact Cassette.
  • Data compression
    See compression(3).
  • Data controller
     A controller change message which is used to set some parameter in the receiving device, for example, the data increment and decrement switches on a synthesizer.
  • Data dump
    A packet of memory contents being transmitted from a sending device to a receiving device, usually in the form of MIDI System-Exclusive data, or stored in RAM. Also called a bulk dump or block transfer.
  • Data slider
    A pot fitted to a device such as a synthesizer which allows parameters within the device to be adjusted for programming, etc.
  • Data thinning
     A sequencer software feature which allows programs and/or devices to reduce the amount of MIDI data produced by continuous controllers such as pitch-bend, aftertouch, etc. This is accomplished by only keeping the continuous controller data when the parameter changes, as opposed to sending all bytes of data all of the time.
  • Datafiler
    A portable device for the replay of previously recorded MIDI data, used in live performances.
  • DAW
    Digital Audio Workstation. See workstation.
  • dB
    See decibel.
  • DB-9 connector
    An industry-standard connector for serial machine control of professional audio and video transports. Developed by Sony, also called the Sony 9-pin.
  • DBS
    Direct Broadcast Satellite. See AC-1.
  • Dbx™ noise reduction
    a noise reduction system that uses a companding noise reduction to reduce noise. Dbx is connected into a recording system in the same way that a Dolby system is. It provides up to 30dB of noise reduction, but unlike Dolby noise reduction, the dbx system works over the entire audio frequency range, using a 2:1/1:2 compression/expansion ratio. Dolby-encoded and dBx-encoded tapes are incompatible. Systems using dbx noise reduction are typically more expensive than systems using Dolby.
  • DCA
     Digitally Controlled Amplifier. Sometimes short for Digitally Controlled Attenuator. The DCA of a digital synthesizer modifies the amplitude of the signal generated by the DCO. It is the digital analog of a VCA.
  • DCA
     Digitally Controlled Amplifier. Sometimes short for Digitally Controlled Attenuator. The DCA of a digital synthesizer modifies the amplitude of the signal generated by the DCO. It is the digital analog of a VCA.
  • DCC
    See Digital Compact Cassette.
  • DCO
    Digitally Controlled Oscillator. The microprocessor-controlled sound generator used in a digital synthesizer. The DCO directly generates the original signal that is used as the fundamental for the sounds created by the synthesizer. The keyboard tells the DCOs what pitch to produce; the audio signal may then be altered by sound modifiers, including a DCW, DCA, differentiators and integrators, and various modulators and limiters. The digital equivalent of the analog VCO.
  • DDL
    Digital Delay Line. See delay line.
  • De-emphasis
    The complementary equalization which follows pre-emphasis. Sometimes redundantly called post de-emphasis.
  • De-esser
    A special type of compressor that operates only at high frequencies, usually above 3kHz-4kHz. It is used to reduce the effect of vocal sibilant sounds. De-essers are usually used only for vocal music.
  • Dead
    Acoustically absorptive. The opposite of live. See also LEDE.
  • Decade
    The interval between two quantities plotted along an axis where the second quantity is ten times the first. A frequency ratio or interval of 10:1, as opposed to an octave, which is a 2:1 ratio. Sometimes the rolloff of a filter or equalizer is expressed in dB/decade, rather than in dB/octave. A rolloff of 20dB/decade is equal to A rolloff of 6dB/octave. The decade interval has no musical significance, but is used in the discussion of logarithmic quantities such as decibels.
  • Decay
     (1) The time it takes for a sound to reach minimum loudness; the end of a sound. (2) The second of the four segments of a typical ADSR envelope. The decay control determines the amount of time it takes for the envelope to fall from the peak reached at the end of the attack segment to the sustain level. If no additional energy is put into the sound source (e.g., a cymbal), then the decay is the time during which the sound falls from the loudest point back to silence. (3) The time taken for reverberation to die away. See decay time, reverberation time,RT-60.
  • Decay rate
     The number of decibels per second by which echoes or reverberation of a sound diminish once the sound has stopped. Depending on the sound source and environment, the decay rate may be linear, i.e., a constantly decreasing number of dB per second, or it may begin to decay slowly and then fall off rapidly, or the reverse. Also, various frequencies of the sound may decay at different rates.
  • Decay time
    See reverberation time.
  • Decca trees
     A triangular array of omnidirectional microphones , a type of true spaced-microphone recording technique, where the central channel is distributed equally to left and right. This yields a very stable central image, avoiding the hole-in-the-middle which is problematic with many space-pair arrangements. A variant on the Decca tree places three cardioid microphones (L,C,R) in a triangle configuration. In all cases, the width of the tree is typically one-half to one-third the sound field width, and the center microphone is slightly closer to the performers. See binaural recording.
  • Decibel (dB)
     A unit of measurement used to indicate audio power level, literally one-tenth of a bel, where the bel is a power ratio of 10:1. Technically, a decibel is a logarithmic ratio of two power measurements, which means that there is no such thing as a dB measurement in isolation. In order to measure a signal in dB, you need to know what power (watts, volts) it is referenced to and the impedance of the reference system. Number of dBs = 10 log (P1/P2), where P1 and P2 are the two powers being compared, and where the log is base-10. Imprecisely, 1dB is the smallest increment in loudness detectable by a careful listener. An increase of about 3dB is a doubling of electrical (or signal) power; an increase of 10dB is ten times more power, but is only a doubling of perceived loudness. Some commonly used power ra-tios, expressed in dB: However, Number of dBs = 20 log (V1/V2), where V1 and V2 are the two voltages being compared, and where the log is base-10. This means that the answer is twice what it would be for a ratio of powers. In other words, dou-ble the voltage and the level goes up by 6dB; halve the voltage and the level goes down by 6dB. See Appendix A.
  • Decimation
    A form of digital filtering whereby audio data is oversampled and then decimated to the required 44.1kHz. In practice, the sampling rate is 64 or 128 times 44.1kHz. A digital brick-wall filter is then applied to the data, resulting in a perfectly phase linear transformation. [This type of filter is impossible in the analog domain due to the phase-shift caused by very steep roll-off filters.] See FIR, IIR. After the data have been filtered below the Nyquist frequency, the next step is decimation where the data are re-sampled to produce an output stream of 44.1kHz, with the attractive result that the excess data thereby provides increased bit-resolution. See anti-aliasing filter, reconstruction filter, DSD.
  • Deck plate
    In a tape recorder transport, the heavy metal plate on which the headstack, rollers, and other transport components are located.
  • Decoding
    (1) In signal processing, restoring a signal to its original state by reprocessing the signal in a complementary manner, e.g., a NR system’s re-expansion of the signal during playback. (2) In digital recording, the entire process converting the encoded data stream back into an analog signal, including the process of error correction, i.e., digital-to-analog conversion.
  • Deconvolution
     A mathematical process for separating two signals that have been convolved. See convolution.
  • Decrescendo
    A musical term indicating a gradual reduction in loudness.
  • Decrescendo
    A musical term indicating a gradual reduction in loudness.
  • Defeat switch
    A control that can be used to mute a signal on a mixer.
  • Definition
     A qualitative term that denotes the clarity of a sound. A sound with poor definition may, like some woodwinds in their middle ranges, be easily mistaken for a similar sound. In recording, the apparent definition of a sound can be increased by boosting the frequency band characteristic to the specific sound of the instrument, and cutting other frequencies it has in common with other sounds in the mix.
  • Delay
     (1) The first stage of a five-stage D(elay)AD(ecay)SR envelope, which delays the beginning of the envelope’s attack segment. See ADSR. (2) An audio effect which temporarily suppresses the beginning of a sound, producing echo, chorusing, phasing, and flanging effects. A modulated digital delay effect which varies the time and/or intensity of the delay effect over time. See double tracking. (3) A signal processor used for flanging, chorusing, and echo, that holds its input for some period of time before passing it to the output, or the algorithm within a signal processor that creates delay. Also used in artificial reverberation systems and to provide delayed sound to certain loudspeakers in time-coherent sound reinforcement systems. (4) See MIDI delay.
  • Delay line
    Used to simulate an acoustic echo or reverberation. There exist both digital delay lines (DDL) and analog delay lines as well. The original delay lines were made by using tape recorders to record a signal while playing it back on the same machine. The distance between the record and reproduce heads causes a time delay; this technique is called tape delay. See tape delay.
  • Delay line
    Used to simulate an acoustic echo or reverberation. There exist both digital delay lines (DDL) and analog delay lines as well. The original delay lines were made by using tape recorders to record a signal while playing it back on the same machine. The distance between the record and reproduce heads causes a time delay; this technique is called tape delay. See tape delay.
  • Delay line feedback
    A type of modulation which creates a series of echoes when the modulation source is boosted. The greater the amount of feedback, the more repetitions of each echoed event.
  • Delta modulation
     In the UK, often, and more properly called delta-sigma modulation. A type of PCM which differs from most other digital encoding schemes in that the signal, after being sampled at a fast rate, is encoded as the difference between successive levels, rather than as the absolute level of each sample. Delta modulation requires a very high sampling rate, usually around 700kHz, but the digital words need for each step contain one bit, whereas conventional PCM samples at only about 45kHz but requires 14-16 bit words. The "delta" phase of delta modulation involves taking the difference of the reconstructed signal and the incoming signal to adjust the output to minimize the quantization error; the "sigma" part involves the summation of the differences to reconstruct the original signal, although there are a number of variant algorithms based on this basic theme. The reason for the popularity of delta modulation-type converters is the inherent linearity of the process. See also ADPCM.
  • Delta modulation
    In the UK, often, and more properly called delta-sigma modulation. A type of PCM which differs from most other digital encoding schemes in that the signal, after being sampled at a fast rate, is encoded as the difference between successive levels, rather than as the absolute level of each sample. Delta modulation requires a very high sampling rate, usually around 700kHz, but the digital words need for each step contain one bit, whereas conventional PCM samples at only about 45kHz but requires 14-16 bit words. The "delta" phase of delta modulation involves taking the difference of the reconstructed signal and the incoming signal to adjust the output to minimize the quantization error; the "sigma" part involves the summation of the differences to reconstruct the original signal, although there are a number of variant algorithms based on this basic theme. The reason for the popularity of delta modulation-type converters is the inherent linearity of the process. See also ADPCM.
  • Delta-Sigma modulation
    See delta modulation.
  • Delta time
    See SMF.
  • Demodulator
    A device that recovers the audio signal from a modulated carrier waveform. Also called a detector. See amplitude modulation and frequency modulation.
  • Depth
    (1) In stereophonic reproduction of music, depth refers to the perceived relative distance between the listener and the various instruments in the sonic image. (2) In a digital delay or flanger, a parameter which modulates the length of delay around the specified delay time. Because this happens in real-time, the pitch of the input signal is varied, causing the output signal to have an apparent vibrato effect. The speed of this vibrato is set by a rate control.
  • Depth perception
    See depth (1)
  • DES
    Dolby-Encoded Stereo. A noise reduction system employed in the reproduction of stereo optical tracks in movie theaters.
  • Desk
    See DAW, mixer.
  • Detector
    (1) See frequency modulation. (2) See level-sensing circuit.
  • Detune
    (1) (noun) A control that allows one oscillator to sound a slightly different pitch than another. (2) (verb) To slightly change the pitch of one oscillator relative to another, producing a fuller sound.
  • DI (Direct Injection)
    Also called a direct box. (1) The use of some form of mechanical or electrical pick-up mechanism on an instrument for the purpose recording or amplification. DI also refers to the connection of an electronic keyboard or power amplifier feeds to a mixer. A DI consists of (usually) a small electronic box into which an instrument is plugged and the electroacoustic pick-up attached to the instrument itself. Pick-ups can be electro-magnetic, as on electric guitars, piezo devices, and also contact microphone, also called bugs. All types of pick-up have unbalanced outputs at mic-level (~-50dBu), so the DI box has to balance the signal and drive it to the mixing desk. DIs can be passive or active in the typical sense. Active DIs have some form of electronic amplification built-in; this is only a buffering amplifier, separating the instrument pick-up from the rest of the DI, yielding no significant gain. Active DIs offer better sound and playability over passive devices, but require batteries, phantom power, or some other means of powering the internal amplifier. (2) Any device used to convert unbalanced lines to balanced lines.
  • Dialog normalization (DN)
    There is a wide difference in the apparent loudness between different TV programs’ audio content. In DTV, with by standard is AC-3 encoded, a program producer chooses one of 31 different dialog normalization (abbreviated DN or "Dialnorm") values and this parameter is carried within the AC-3 datastream, where each step represents a 1dB change in level. The DN value is the difference in dB between the maximum level possible (0 dBFS) and the average loudness level of the program material. The smaller the difference between the maximum and program average levels, the lower the DN value is assigned. The lower the DN value, the lower the output volume of the AC-3 decoder is set in direct proportion, meaning that subjectively louder programs will be played back at lower volumes than those in which the average program level is less loud. This supposedly will obviate the user having to adjust the volume control between programs, once the audio listening level is set by the user.
  • Dialog track
    The edited track on magnetic film containing the dialog portion of a film’s sound. Sometimes there may be a separate track for each actor in a scene, requiring the tracks to be mixed down to a single track. The "D "part of DME.
  • Diaphragm
     The membrane part of a microphone’s capsule or cone of a loudspeaker that moves in response to sound waves or an incoming signal, respectively.
  • Diatonic
    A musical scale of eight notes spanning one octave, consisting of an ascending pattern of two whole-steps, a half-step, three whole-steps and another half-step. There are two types of diatonic scale in common use in western music: the diatonic major scale and the diatonic minor scale. Music which includes notes outside of the diatonic in which the piece is written is said to be chromatic.
  • Diatonic comma
    After playing the Circle of Fifths, i.e., twelve ascending perfect fifths, followed by seven descending octaves, the pitch discrepancy between the ending note and the starting note is called the diatonic comma, or the Comma of Pythagoras. This discrepancy amounts to a little over 1%, or about one-sixth of a half-step and gives rise to various temperaments in an attempt to distribute the error as harmoniously as possible. See scale construction, syntonic comma.
  • Diatonic comma
    After playing the Circle of Fifths, i.e., twelve ascending perfect fifths, followed by seven descending octaves, the pitch discrepancy between the ending note and the starting note is called the diatonic comma, or the Comma of Pythagoras. This discrepancy amounts to a little over 1%, or about one-sixth of a half-step and gives rise to various temperaments in an attempt to distribute the error as harmoniously as possible. See scale construction, syntonic comma.
  • Dichotic
    Dichotic generally refers to headphone listening where each ear hears a different signal, as opposed to diotic, where both ears hear the same signal. See also monotic.
  • Difference tone
    A tone produced by combining two tones which are not part of a harmonic series, having a frequency difference of 20Hz or greater. Any slower than 20Hz, and the difference of the two notes will be perceived as a pulse, called beating. Also called a resultant tone. Also called a Tartini tone.
  • Differential amplifier
    Usually one of the signal input terminals of an amplifier is connected to the chassis of the amplifier, i.e., it is grounded. The amplifier is then sensitive to the voltage difference between the input terminal and ground. However, in a differential amplifier, neither input terminal is grounded. Instead, the amplifier is sensitive to the voltage difference between the two inputs. Used in professional microphone preamplifier where a low-level signal has to go some distance, a differential amplifier cancels the hum induced by the proximity of the two input wires to a source of interference. In the UK, a differential amplifier is called an inverting amplifier. See differential input, common mode.
  • Differential input
    Signal input response to amplitude differences between two out-of-phase signals. Used in a balanced wiring system where the two wires carry signals that are identical, but 180° out-of-phase. The phase difference means that as a signal increases in voltage along one line, its mirror image on the other line decreases. This is useful because signals, such as hum and noise which have accumulated along a cable acting as an antenna, that are in phase are cancelled. See common mode, differential amplifier.
  • Differential output
    The output of an amplifier designed to provide two signals that are completely identical, but of opposite phase.
  • Differentiator module
    A highpass filter which can accentuate the higher-frequency harmonics and transients of a sound envelope. Compare with an integrator module.
  • Diffraction
    The bending of a sound wave around an obstacle and the reflection of a sound wave from an obstacle in its path are called diffraction. It is frequency dependent. Where the wavelength is short compared to the obstacle, reflection will occur as well as bending of the wave front. When the wavelength is long with respect to the obstacle, little reflection will occur and the bending will be more pronounced. See also refraction.
  • Digital
    In audio, the opposite of analog. The representation of audio or video as a series of encoded binary amplitude values, rather than as a continuous waveform.
  • Digital Acoustics Processor
    A consumer audio device that attempts to simulate the acoustics of an auditorium or other room by adding suitable time delays and synthetic reverberation to recorded signals.
  • Digital audio
    The application of digital technology to the recording, processing, and reproduction of music is somewhat loosely called digital audio, as opposed to analog.
  • Digital Audio Broadcasting
    An alternative to AM and FM broadcasting with audio quality comparable to that of the CD, it does not suffer from fringe area fading or multipath distortion, and requires less radiated power than conventional broadcasting (1kW versus 50kW for AM and up to 100kW for FM.)
  • Digital Audio Extraction
    See grabbing
  • Digital Audio Mastering System
    See Digital multitrack.
  • Digital Audio Recorder
     Any type of audio recording system which records upon a digital medium, such as DAT or hard disk. DAT or DCC recorders, digital dubbers, digital multitracks, and hard-disk recording systems are all example of digital audio recorders. These recorders are an alternative to analog recorders, such as traditional cassette or reel-to-reel formats which do not convert the waveform to a digital representation prior to writing it to the recording medium.
  • Digital Audio Recorder (DAR)
    Any type of audio recording system which records upon a digital medium, such as DAT or hard disk. DAT or DCC recorders, digital dubbers, digital multitracks, and hard-disk recording systems are all example of digital audio recorders. These recorders are an alternative to analog recorders, such as traditional cassette or reel-to-reel formats which do not convert the waveform to a digital representation prior to writing it to the recording medium.
  • Digital black
     In digital audio, a term which means complete silence. Digital black is calculated by taking the sample word length (e.g., 16, 20, or 24 bits) and multiplying this bit depth by 6dB, a number which represents the dynamic range represented by one bit. In a 16-bit system, for example, full code represents 96dB, the maximum amplitude that the system is capable of encoding without clipping. Digital black is at the opposite end of that dynamic range, or 96dB down from full code amplitude.
  • Digital Compact Cassette
    A type of recording format announced by Philips in 1990, designed to compete with the R-DAT format. The system allows for the recording and playback of analog cassettes as well as DCCs on the same machine. Uses PASC (Precision Adaptive Subband Coding), derived from the MPEG-1, Layer 1 data reduction system to provide data compression (lossy) for the recording of digital audio on wide magnetic tape at ips. This format has not been widely adopted. Sometimes called DCAC for Digital Audio Compact Cassette. See also MiniDisc, DAT, and CD.
  • Digital Compact Cassette
    A type of recording format announced by Philips in 1990, designed to compete with the R-DAT format. The system allows for the recording and playback of analog cassettes as well as DCCs on the same machine. Uses PASC (Precision Adaptive Subband Coding), derived from the MPEG-1, Layer 1 data reduction system to provide data compression (lossy) for the recording of digital audio on wide magnetic tape at ips. This format has not been widely adopted. Sometimes called DCAC for Digital Audio Compact Cassette. See also MiniDisc, DAT, and CD.
  • Digital dubbers
    Film industry term for a multitrack digital recorder, usually having eight tracks per unit, that use removable hard drives or magneto-optical drives as the recording medium. The term is partly a misnomer because previous film sound terminology had used dubber to describe a copying device as opposed to a recording device.
  • Digital Multitrack
    A device for recording multiple channels of digital audio data at various sampling rates. Two formats have survived: the Sony/Studer DASH format and MDM machines of either ADAT or DTRS type. The first digital multitrack recorder was introduced in the late 1970s by 3M, a 32-track recorder called the Digital Audio Mastering System.
  • Digital multitrack
    A device for recording multiple channels of digital audio data at various sampling rates. Two formats have survived: the Sony/Studer DASH format and MDM machines of either ADAT or DTRS type. The first digital multitrack recorder was introduced in the late 1970s by 3M, a 32-track recorder called the Digital Audio Mastering System.
  • Digital Signal Processing DSP
    The manipulation and modification of signals in the digital domain, possibly after having undergone analog-to-digital conversion.
  • Digital TeleVision (DTV)
    See DTV
  • Digital TeleVision (DTV)
    DTV’s audio specification provides up to six discrete channels of 5.1-format audio, where the LFE channel is band-limited to 25Hz-120Hz. DTV has been developed specifically for the home theater market, as an improvement to the ProLogic system.
  • Digital time delay
    See delay.
  • Digital-to-analog converter
    Commonly abbreviated D/A, D/A converter or DAC. A device that changes the sample words put out by a digital audio device into analog fluctuations in voltage that can be sent to a mixer, amplifier, or speaker. All digital synthesizers, samplers, and effects devices have DACs at their outputs to create audio signals, as the transducers in loudspeakers are inherently analog devices.
  • Digital watermark
    The solution for a piracy and duplication protection scheme developed jointly by Sony and Philips which writes copyright data encrypted within the CD/DVD etc. disc itself. This scheme would, for example, encode discs with a country code so that these discs would only play on players from the same country. This is presumably better than older forms of digital copy protection which tried various pilot tones or random number generators, failing ultimately because the results were either too audible or too easy to circumvent. In a digital watermark, the copyright data are stored as a modulation of the width of the injection-molded pits. Duplicating the watermark would require the same equipment as that which produced the disc stamper, the distribution of which is presumably tightly controlled. It is also possible to synchronize the modulation of the pit widths so that there is a visible pattern formed on the disc pit substrate itself, making an "analog" watermark (without the need for water, of course.) In addition to the watermark and country codes, identifiers for the mastering house and pressing plant, glass master number, ISRC catalog numbers, etc. can be stored. The digital watermarking technology has been called Pit Signal Processing (PSP) which works by modulating the strength of the laser used to record the digital data onto the glass master. One by-product of the watermarking process is that the EFM used to encode audio data onto the CD master allows the pits to vary in length between 3-11 units. These slight errors in length, or "jitter" result in slight timing errors which can cause a smearing of the stereo image as well as an increase in HF noise. The more rigid requirements of pit length control in watermarking should result in a significant reduction of pressing-induced jitter, just generally improving the CD production process.
  • DigitalDolby Theater Systems (DTS)
    A 5.1-format theater surround-sound system which uses six A six-channel discrete analog channels and for surround-sound on a CD-ROM interlocked to either a 35mm or a 70mm print with timecode. Lossless. The DTS codec provides for data rates from 256kbps to 1536kbps, focusing on 1141kbps as the optimum for transparent sound quality. DTS was originally developed for the film industry, however, there are a number of CD titles currently released in DTS format. A DTS CD carries six channels of digital audio in 5.1 format in 20-bit words at a 44.1kHz sample rate, with a compression ratio of about 3:1. An additional decoder is needed to play a DTS CD on a standard CD player. First used in 1993 for the film, "Jurassic Park." See also Dolby Digital Surround Sound, Dolby Stereo.
  • Digitally controlled amplifier
    See DCA.
  • Digitally Controlled Oscillator (DCO)
    The microprocessor-controlled sound generator used in a digital synthesizer. The DCO directly generates the original signal that is used as the fundamental for the sounds created by the synthesizer. The keyboard tells the DCOs what pitch to produce; the audio signal may then be altered by sound modifiers, including a DCW, DCA, differentiators and integrators, and various modulators and limiters. The digital equivalent of the analog VCO.
  • Digitally Controlled Waveshape
    A DCW varies the timbre of synthesized sound by modifying the harmonic content of the tone produced by a DCO. See waveform.
  • Diminuendo
    Synonym for decrescendo.
  • Diminution
     (1) The reduction of a major or perfect interval by one half-step to make a diminished interval. (2) The appearance of a musical idea in note durations that are shorter than those used for its first appearance. The opposite of augmentation. (3) A method ornamentation where notes of long duration are broken into a number of shorter notes, often at different pitches, e.g., a trill.
  • DIN
     Deutsche Institut für Normung. A German standards organization that proposed a set of connector configurations in the early 1960s. The standard MIDI connector is the 5-pin DIN where:
  • DIN Sync
    See pilot tone.
  • Diode
    A circuit element that will pass current in one direction only, from the anode (positive) to the cathode (negative). Used to make DC from AC.
  • Diotic
    Literally, "with two ears." Diotic generally refers to headphone listening whereby the two ears hear the same signal, as opposed to monotic, where only one ear hears the signal. See also dichotic.
  • Dip filter
    A parametric equalizer with an extremely narrow Q, designed to remove noise in a small band such as that from a camera or light.
  • Dipole
    In loudspeaker design, a dipole radiator is a system which radiates forwards and rearwards with equal energy, but with opposite polarity. Examples of dipole radiators are electrostatic loudspeakers and planar speakers. Some cone-type speakers have dipole radiators. For a dipole radiator to have adequate low-frequency response, it must be very large to prevent the rear wave from canceling the front wave. Also, the dipole radiator must not be placed close to and parallel to a wall, working best when not near reflective surfaces.
  • Direct box
    See DI.
  • Direct coupling
     A connection between two devices that allows both DC and AC between them.
  • Direct current
    Current in only one direction. DC always has the same direction, from the positive to the negative terminal. Compare with AC.
  • Direct field
    See reverberant field.
  • Direct Metal Mastering (DMM)
    A system for cutting a metal mother on a record mastering lathe, eliminating the lacquer master and metal master steps. Release pressings made from a stamper are thus only two stems from the DMM and thus have less noise and distortion than those made by the older, five-step process. The DMM process is also used in CD mastering.
  • Direct output
     A recording console output taken directly after the input module and main channel fader, but before the panpot and output bus assignment switches. This output is sometimes used to avoid crosstalk that may be introduced if the signal is allowed to flow through the complete circuit.
  • Direct positive
     A optical (photographic) sound recording that, when processed, results in a track that can be played and edited; now obsolete.
  • Direct radiator
    A loudspeaker which does not have a horn between the moving element and the air is called a direct radiator. Most direct radiator-type speakers are for home use, while horn-type speakers are preferred for sound reinforcement applications. Direct radiators generally provide smoother, more uniform response, while horns are much more efficient, providing a greater output level for a given power input. Also, horns have greater directivity, which is desirable in sound reinforcement systems. See compression driver.
  • Direct sound
    (1) See reverberant field. See also free-field, critical distance. (2) The sound received at the recording console from an electronic instrument when using a direct box.
  • Direct Stream Digital™
    : A proprietary CD/DVD data format proposed by Sony and Philips for use in the SACD . DSD bandwidth is normally 2.844Mb per channel (64 times 44.1kHz), with optional sampling rates of 32 or 128 times 44.1kHz,yielding a slightly higher data rate than that required by 24-bit/96 kHz resolution conventional A/D-D/A systems. DSD uses a delta modulated ADC to generate a 2.8224MHz, 1-bit signal, a rate chosen as a simple multiple of the lowest common high-fidelity PCM sampling rate, 44.1kHz. The 1-bit datastream is recorded directly to disk, avoiding the decimation and oversampling stages, inherently improving the resultant audio quality, simplified error protection, and there is no need to frame the data into words. Sony claims that the sampling rate is so high that it more nearly approximates the original analog signal, allowing equalizers and other effects processors to better simulate analog effects. It is claimed that DSD can have frequency response up to 1MHz, or up to a dynamic range (within the audio bandwidth) of 120dB, equivalent to about a 20-bit resolution. A number of DSP algorithms are available which allow the optimization of either bandwidth or dynamic range. [Note that these benefits apply only to those players which support the DSD standard, as a replay on any conventional CD, DVD or another digital format would require the decimation and framing steps.]
  • Direct Stream Digital™
    A proprietary CD/DVD data format proposed by Sony and Philips for use in the SACD . DSD bandwidth is normally 2.844Mb per channel (64 times 44.1kHz), with optional sampling rates of 32 or 128 times 44.1kHz,yielding a slightly higher data rate than that required by 24-bit/96 kHz resolution conventional A/D-D/A systems. DSD uses a delta modulated ADC to generate a 2.8224MHz, 1-bit signal, a rate chosen as a simple multiple of the lowest common high-fidelity PCM sampling rate, 44.1kHz. The 1-bit datastream is recorded directly to disk, avoiding the decimation and oversampling stages, inherently improving the resultant audio quality, simplified error protection, and there is no need to frame the data into words. Sony claims that the sampling rate is so high that it more nearly approximates the original analog signal, allowing equalizers and other effects processors to better simulate analog effects. It is claimed that DSD can have frequency response up to 1MHz, or up to a dynamic range (within the audio bandwidth) of 120dB, equivalent to about a 20-bit resolution. A number of DSP algorithms are available which allow the optimization of either bandwidth or dynamic range. [Note that these benefits apply only to those players which support the DSD standard, as replay on any conventional CD, DVD or other digital format would require the decimation and framing steps.
  • Direct Stream Transfer™
    Philips’ proprietary technology for lossless 2:1 data reduction in digital recordings on SACD. DST is optimized for audio-type signals, allowing sufficient storage capacity for double the old CD standard of 74 stereo minutes. By incorporating DST into the SACD standard, it is possible to store two complete 74-minute versions of audio material so as to combine a stereo DSD track, and a 6-channel surround mix, plus other data, text, graphics, and video, all on the single, high-density DASD layer.
  • Direct Stream Transfer™ (DST)
     Philips’ proprietary technology for lossless 2:1 data reduction in digital recordings on SACD. DST is optimized for audio-type signals, allowing sufficient storage capacity for double the old CD standard of 74 stereo minutes. By incorporating DST into the SACD standard, it is possible to store two complete 74-minute versions of audio material so as to combine a stereo DSD track, and a 6-channel surround mix, plus other data, text, graphics, and video, all on the single, high-density DASD layer.
  • Direct-to-disc
     A type of analog LP mastering in which a master tape is not used. The signal directly from the control console is used to cut the original acetate disc. This means a direct-to-disc recording cannot be edited, and is made live. (2) Recording digital audio data onto a hard disk for replay or editing.
  • Direct-to-two-track
    A method of recording in which the instruments and vocals are mixed and recorded directly onto a stereo half-track or DAT. If analog, no further changes or remixing is possible. The fidelity, edibility, and relatively low-cost of direct-to-two-track digital recording has revived the popularity of this medium for making master tapes, especially those intended for release on CDs. Also called live-to-two-track.
  • Directional microphone
    A microphone which does not have a spherical polar pattern, i.e., a microphone which is not omnidirectional, such as a cardioid, figure-eight, etc. having an acceptance angle of less than 360¢ª. See directivity.
  • Directivity
    Describes the angle of coverage of a loudspeaker system or microphone acceptance angle, both in the vertical and horizontal planes. High directivity equates to a narrow angle of coverage. The directivity factor is a measure of the directionality of the sound output of a loudspeaker. See also Q.
  • DirectX
    A collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. Originally, the names of these APIs all began with "Direct", such as Direct3D, DirectDraw, DirectMusic, DirectPlay, DirectSound, and so forth. The most common audio effects plug-in format used by Windows™ software.
  • Discrete
     Refers to a 1:1 relationship of recorded tracks on an audio medium or film print and the resulting number of speaker channels. Contrast with matrixed sound.
  • Discrete 6-track
     Traditionally means the five-speakers-behind-the-screen system made popular by the Todd-AO 70mm process (although first used for Cinerama). Today the term sometimes means six nonmatrixed tracks, assigned to L,C,R,LS,RS,Subwoofer. See also 5.1.
  • Discrete 6-track
    Traditionally means the five-speakers-behind-the-screen system made popular by the Todd-AO 70mm process (although first used for Cinerama). Today the term sometimes means six nonmatrixed tracks, assigned to L,C,R,LS,RS,Subwoofer. See also 5.1.
  • Discrete output
    A direct output from a mixer channel, which services only that one channel.
  • Discrete output
     A direct output from a mixer channel, which services only that one channel.
  • Disk-at-once
    A CD production process where the entire disc is written in one burn; the laser is never turned off. Ideal for audio, disk-at-once mode allows gaps between tracks of any length (except the first track, which must have a 2-3 second gap.) Compare with track-at-once.
  • Disk-at-once
    A CD production process where the entire disc is written in one burn; the laser is never turned off. Ideal for audio, disk-at-once mode allows gaps between tracks of any length (except the first track, which must have a 2-3 second gap.) Compare with track-at-once.
  • Dispersion
    (1) The spreading of sound waves as they leave a loudspeaker. (2) Another term for refraction.
  • Dispersion
     (1) The spreading of sound waves as they leave a loudspeaker. (2) Another term for refraction.
  • Displacement
    The distance between some measured position of a moving object, e.g., a speaker cone, and its static position. Also applies to the position of air molecules in a sound wave. See rarefaction.
  • Distant miking
     The opposite of close miking. In recording, the placement of one or more microphones relatively far away from the sound source. This technique picks up a substantial portion of reverberant sound, and is therefore used to make most classical or orchestral recordings to capture the sound as closely as possible to that experienced by an audience. In the studio, close and distant mics on any instrument or group may be blended at the mixer to achieve the desired sonic image. See depth.
  • Distant miking
    The opposite of close miking. In the recording, the placement of one or more microphones relatively far away from the sound source. This technique picks up a substantial portion of the reverberant sound and is therefore used to make most classical or orchestral recordings to capture the sound as closely as possible to that experienced by an audience. In the studio, close and distant mics on any instrument or group may be blended at the mixer to achieve the desired sonic image. See depth.
  • Distortion
    Also called correlated noise. Any (usually) unwanted sound which varies with the input signal. (1) Any undesirable change in the characteristics of an audio signal of six types: The two types of (i) nonlinear distortion are intermodulation distortion and harmonic distortion. Other types of distortion are (ii) frequency distortion (pitch-shift), (iii) phase distortion (time shift), (iv) transient distortion,(v) scale (volume) distortion, and (vi) frequency modulation distortion. There are other factors which cause music reproduction to be untrue to the original but which are not considered distortion, such as background noise, and a lack of directional realism and proper ambience due to the use of too few channels of reproduction. See noise. (2) A sound modulation technique whereby the original waveform is distorted intentionally.
  • Distortion
     Also called correlated noise. Any (usually) unwanted sound which varies with the input signal. (1) Any undesirable change in the characteristics of an audio signal of six types: The two types of (i) nonlinear distortion are intermodulation distortion and harmonic distortion. Other types of distortion are (ii) frequency distortion (pitch-shift), (iii) phase distortion (time shift), (iv) transient distortion,(v) scale (volume) distortion, and (vi) frequency modulation distortion. There are other factors which cause music reproduction to be untrue to the original but which are not considered distortion, such as background noise, and a lack of directional realism and proper ambience due to the use of too few channels of reproduction. (2) A sound modulation technique whereby the original waveform is distorted intentionally. See noise.
  • Dither
     A noise-based rounding method used to add a tiny amount of controlled noise to a digital audio file to make other, more objectionable errors less obvious and/or to convert from one word size down to a smaller word, e.g., from 24-bit resolution to 16-bits. Redithering is a dithering process used in digital-to-digital signal processing to distinguish it from the dithering process used during the original A/D conversion. There are several ways to dither: Add white noise at about half or one-third the value of the LSB, or half the level that a system can transmit. Thus, for a 16-bit converter encoding a range of 2V, the LSB is equivalent to a difference of 30.5µV (2÷65,536V), yielding dithered noise of about 10-15µV;Second-Order dither in which the dither signal (white noise) is processed by a highpass filter to remove low-frequency components. This makes the noise less appar-ent to the ear, since humans are less sensitive to high-frequency noise than other lev-els;Noise-shaping in which the dither signal is run through a set of filters to provide the most energy in regions where the ear is the least sensitive;(Triangular Probability Density Function) where before the noise is shaped, it has a different spectral content than ordinary white noise. It has better noise modulation performance, which is how the noise affects the signal itself;Sony’s SBM (Super Bit-Mapping) where the audio is run through a processor with an algorithm that maps a series of higher-resolution samples to a series of lower-resolution samples;The Apogee UV-22, which is not really dither. Instead, it uses a periodic signal centered around 22kHz that has good performance in terms of audibility and noise modulation. Placing the signal this high in the audio spectrum makes it very difficult to hear and produces fewer effects on the character of the signal.
  • Dither
    A noise-based rounding method used to add a tiny amount of controlled noise to a digital audio file to make other, more objectionable errors less obvious and/or to convert from one word size down to a smaller word, e.g., from 24-bit resolution to 16-bits. Redithering is a dithering process used in digital-to-digital signal processing to distinguish it from the dithering process used during the original A/D conversion. There are several ways to dither: Add white noise at about half or one-third the value of the LSB, or half the level that a system can transmit. Thus, for a 16-bit converter encoding a range of 2V, the LSB is equivalent to a difference of 30.5µV (2÷65,536V), yielding dithered noise of about 10-15µV;Second-Order dither in which the dither signal (white noise) is processed by a highpass filter to remove low-frequency components. This makes the noise less apparent to the ear, since humans are less sensitive to high-frequency noise than other levels;Noise-shaping in which the dither signal is run through a set of filters to provide the most energy in regions where the ear is the least sensitive;(Triangular Probability Density Function) where before the noise is shaped, it has a different spectral content than ordinary white noise. It has better noise modulation performance, which is how the noise affects the signal itself;Sony’s SBM (Super Bit-Mapping) where the audio is run through a processor with an algorithm that maps a series of higher-resolution samples to a series of lower-resolution samples;The Apogee UV-22, which is not really dither. Instead, it uses a periodic signal centered around 22kHz that has good performance in terms of audibility and noise modulation. Placing the signal this high in the audio spectrum makes it very difficult to hear and produces fewer effects on the character of the signal.
  • DLL
    Dynamic Link Library. Files used by PC-type computer application programs to provide additional functionality to the computer’s operating system. The equivalent of an extension file on a Mac.
  • DLL
    Dynamic Link Library. Files used by PC-type computer application programs to provide additional functionality to the computer’s operating system. The equivalent of an extension file on a Mac.
  • DLS-2
     Downloadable Sounds Level 2. An improvement over DLS which moves closer to enabling multitrack audio and MIDI programs to be used by audio and MIDI hardware and software interchangeably. This is accomplished by transferring entire multisampled instruments, along with the MIDI data, to the end-user’s platform, resulting in playback as the author intended. In addition to the specification of DLS-1, DLS-2 specifies: resonant filter control, adds delay and hold to envelope segments, effects routing for chorus and reverb, no limit to the number of regions in any soundbank, each reason can have independent envelope and filter data, and is extensible to include other forms of synthesis. Ratified by the MMA in early 1999. See also MPEG-4.
  • DLS-2
     Downloadable Sounds Level 2. An improvement over DLS which moves closer to enabling multitrack audio and MIDI programs to be used by audio and MIDI hardware and software interchangeably. This is accomplished by transferring entire multisampled instruments, along with the MIDI data, to the end-user’s platform, resulting in playback as the author intended. In addition to the specification of DLS-1, DLS-2 specifies: resonant filter control, adds delay and hold to envelope segments, effects routing for chorus and reverb, no limit to the number of regions in any soundbank, each reason can have independent envelope and filter data, and is extensible to include other forms of synthesis. Ratified by the MMA in early 1999. See also MPEG-4.
  • DLS
    DownLoadable Samples. A standard which allows multimedia games or other programs to contain samples which would be downloaded to the playback hardware. This is a hybrid between streaming digital audio (direct audio from CD-ROM, for example) and MIDI, which alters predefined sounds. DLS is an attempt to solve the problems inherent in the ambiguity of the GM specification and the somewhat random sounds produced by the playback hardware. DLS-1 specifies: 16-zone multisampled soundbanks with 128 zones for drum banks, pitch-shifting, ADSR for amplitude and pitch, and LFO for amplitude or pitch. DLS-1 was ratified by the MMA in 1997. See DLS-2.
  • DLT
    Digital Linear Tape. A tape-based computer backup format developed by Quantum Laboratories.
  • DLT
    Digital Linear Tape. A tape-based computer backup format developed by Quantum Laboratories.
  • DMA
    Direct Memory Access. A digital logic design which allows peripheral devices to communicate directly with the system memory, rather than requiring the central processor to stop whatever processing it was doing to control communications between an attached device (usually having some kind of I/O function) and the computer memory.
  • DMA
    Direct Memory Access. A digital logic design which allows peripheral devices to communicate directly with the system memory, rather than requiring the central processor to stop whatever processing it was doing to control communications between an attached device (usually having some kind of I/O function) and the computer memory.
  • DME
    Dialog, Music, and Effects. The three basic stems of film soundtracks, originally meant to denote the 35mm 3-track master mix of academy mono films.
  • DME
     Dialog, Music, and Effects. The three basic stems of film soundtracks, originally meant to denote the 35mm 3-track master mix of academy mono films.
  • DME
    Dialog, Music, and Effects. The three basic stems of film soundtracks, originally meant to denote the 35mm 3-track master mix of academy mono films.
  • DN (Dialog Normalization)
    There is a wide difference in the apparent loudness between different TV programs’ audio content. In DTV, with by standard is AC-3 encoded, a program producer chooses one of 31 different dialog normalization (abbreviated DN or "Dialnorm") values and this parameter is carried within the AC-3 datastream, where each step represents a 1dB change in level. The DN value is the difference in dB between the maximum level possible (0 dBFS) and the average loudness level of the program material. The smaller the difference between the maximum and program average levels, the lower the DN value is assigned. The lower the DN value, the lower the output volume of the AC-3 decoder is set in direct proportion, meaning that subjectively louder programs will be played back at lower volumes than those in which the average program level is less loud. This supposedly will obviate the user having to adjust the volume control between programs, once the audio listening level is set by the user.
  • DNR
    Dynamic Noise Reduction. Similar to Dolby, but was not effective.
  • Dolby Digital™
    The 5.1-channel digital format created by Dolby Laboratories, first used in 1992 for "Batman Returns." In current usage, the term applies to both the Dolby 35mm theatrical format, which contains the data printed optically between the sprocket holes, and for video formats, such as DVD, laserdisc, and DTV. AC-3, as Dolby Digital was first called, used RF modulation of the digital signal onto one of the analog tracks, making it possible to fit an entire movie, along with the already existing digital tracks, onto a conventional laserdisc; a demodulator was needed to recover the audio back into a digital bitstream. The Dolby Digital format is a surround-sound, split-band, perceptual coding scheme. AC-3 was designed as a 5.1 multichannel format , using approximately 13:1 lossy compression, and is specified as the matrixing format for DVD and DTV. Also used in HDTV broadcasts, SR-D, and DSD cinema productions. Versatile, in that parameters such as bit-rate and number of channels can be tailored to particular applications, unique in that the data bits are distributed dynamically among the filter bands as needed by the particular frequency spectrum or dynamic nature of the program. Data rates vary from 32kbps for a single mono channel to as high as 640 kbps for 5.1 format. The data rate is 320kbps for film, 384kbps for laserdisc, and 384kbps or 448kbps for DVD, although the maximum throughput for the specification is 640kbps. Dolby’s current decoder can accept incoming data at 32kHz, 44.1kHz, or 48kHz sample rates, with bit depths of 16, 18, or 20 bits. The commercial competitor to the Dolby Digital format is DTS. See metadata, audio coding mode.
  • Dolby Fax
    See ISDN.
  • Dolby Motion Picture 4:2:4
    A matrixed surround-sound system which combines multichannel LCRS audio in such a way that the encoded signal forms a stereo-compatible, two-channel format for recording and broadcasting. Originally developed in 1977 for "Star Wars," and now in wide use. As with any matrix system, it is impossible to completely recover the original multichannel signals with perfect isolation. The decoder disguises this problem through a steering process which emphasizes the signal emanating from its appropriate loudspeaker by canceling out a portion of the crosstalk in adjacent channels. See also free encoding, Pro Logic.
  • Dolby noise
    The Dolby SR analog allows the comparison of the recorded Dolby noise on a tape to that generated by the decoder, with four continuous seconds of noise to identify the generator, and two 2-second sections of noise indicating that the monitoring is off-tape. This allows for confirmation of correct EQ settings as well as playback verification. The broadband reference signal used to correctly calibrate the different Dolby codecs is called Dolby noise. See Dolby tone.
  • Dolby noise reduction
     A type of two-ended, dynamic noise reduction for magnetic tape recording and playback. The essential difference between a compander and the Dolby system is that the Dolby system is frequency-dependent. The compander was developed to reduce distortion. Dolby applies companding to frequency variations in addition to signal amplitude variations, adjusting gain as frequency changes. The Dolby-A and Dolby-SR systems are used for professional recording in studios. Consumer tape decks use either a Dolby-B or Dolby-C system. Dolby-B operates only at high frequencies and reduces tape hiss by about 10dB. Dolby-C works over a slightly wider frequency range, providing a noise reduction of up to 20dB. All of the Dolby systems operate on quiet passages, below levels of about -10VU. Very strong signals, such as over 60dB or at frequencies below 500Hz are not affected by the Dolby system because these signals are not degraded by tape noise. When the recorded signal is played back, the Dolby circuit reduces the accentuated high-frequency signals so that the frequency response of the record/playback system is flat, hence reducing also the high-frequency tape hiss, improving the S/N ratio of the taped music. See asperity, Barkhausen effect, compander, dbxcompander,dbx, spectral recording.
  • Dolby noise reduction
    A type of two-ended, dynamic noise reduction for magnetic tape recording and playback. The essential difference between a compander and the Dolby system is that the Dolby system is frequency-dependent. The compander was developed to reduce distortion. Dolby applies companding to frequency variations in addition to signal amplitude variations, adjusting gain as frequency changes. The Dolby-A and Dolby-SR systems are used for professional recording in studios. Consumer tape decks use either a Dolby-B or Dolby-C system. Dolby-B operates only at high frequencies and reduces tape hiss by about 10dB. Dolby-C works over a slightly wider frequency range, providing a noise reduction of up to 20dB. All of the Dolby systems operate on quiet passages, below levels of about -10VU. Very strong signals, such as over 60dB or at frequencies below 500Hz are not affected by the Dolby system because these signals are not degraded by tape noise. When the recorded signal is played back, the Dolby circuit reduces the accentuated high-frequency signals so that the frequency response of the record/playback system is flat, hence reducing also the high-frequency tape hiss, improving the S/N ratio of the taped music. See asperity, Barkhausen effect, compander, dbxcompander,dbx, spectral recording.
  • Dolby ProLogic™
     A four-channel perceptual coding scheme developed by Dolby Labs where an LCRS audio signal is converted into two channels of analog audio, then recovered to yield discrete left, center, right, and mono surround channels. This is a hardware version of their surround decoder originally developed for the Dolby Motion Picture 4:2:4 matrix surround-sound system, developed for the Star Wars picture in 1977. If a subwoofer is used, it is generally fed by lowpass-filtering a mix of the three front channels at the receiver.
  • Dolby SR™
    A complex type of two-ended, dynamic split-band, noise reduction compander system that outperforms Dolby-A, -B, or -C systems and also results in reduced distortion in most cases. This was developed as an upgrade to the professional Dolby-A, featuring an improvement in tracking accuracy and sliding bands, and closest to C-type noise reduction. S-Type noise reduction is the consumer analog. See SR.D.
  • Dolby SR.D™
     A system developed by the Dolby company for placing a digital audio soundtrack onto 35mm film, first used in 1992. The soundtrack includes a Dolby Digital mix, as well as an SR analog stereo optical track. The data are compressed and printed onto the film between the sprocket holes. See surround-sound, perceptual coding, Dolby surround-sound, spectral recording.
  • Dolby Stereo™
     The original Dolby Surround system which used four audio channels carried on a stereo optical track on 35mm film, using Dolby perceptual encoding. On 70mm film, six audio channels are recorded on discrete magnetic tracks laid onto the film. In the broadest and most common usage, the trademark that appears on movie prints, advertisements, and posters which means that a given film has been released in prints that employ Dolby A-Type noise reduction encoding. Beginning in 1987, Dolby-SR has been available on 35mm stereo optical prints. Dolby Stereo on 70mm usually means four discrete primary channels (LCRS) with the left-center and right-center tracks dedicated to low-frequency information (below 250 Hz). The four tracks are normally use A-Type encoding, although selected 70mm films, since 1987, have utilized Dolby-SR encoding. See film soundtrack.
  • Dolby Surround EX™
    The digital release format developed by Dolby Laboratories and THX for use in "Star Wars: Episode One--The Phantom Menace." Three surround tracks are derived by matrix-encoding them in the two previously existing surround tracks. This should not be referred to as a 6.1-channel format because the additional surround channel is not a discrete channel.
  • Dolby tone
    A reference tone, usually recorded at the head of a Dolby-A recorded tape, by which the threshold levels of the Dolby noise reduction system are adjusted for proper encoding and decoding of the companded signal.
  • Domain
     In magnetic recording tape, the smallest ferric oxide particle that can be considered as a separate magnet. Defined as molecules of ferric oxide, or, less than one billionth of a gram of material. See Barkhausen effect.
  • Dominant
    See Circle of Fifths, key.
  • Dongle
    A hardware device that plugs into a parallel or a USB port, acting as copy protection for a particular software application.
  • Doppler effect
     The apparent change in the pitch of a sound when the source of the sound is moving with respect to the listener. Also called Doppler distortion.
  • DOS
    Disk Operating System. The original operating system for PC-type computers. Much of the Windows™ operating system is written in DOS; NT is not.
  • Double-system sound
    (1) A method of producing sound motion pictures where the soundtracksound track is recorded on a magnetic tape recorder which is separate from the video recorder and which is synchronized with the movement of the film in the camera, projecting a film with the picture on 35mm film, in interlock with the soundtrack, most commonly on mag film. The synchronization was originally done by recording a special tachometer signal on one track of the tape, but is now done with timecode. Examples of double-system sound are film and Nagra, film and mag dubber, videotape and audio tape. (2) A film or video production that utilizes sound recorded on a separate tape recorder, such as a DAT or Nagra. This term is still used even if the video recorder is also simultaneously recording the sound. Compare with single sound system. See mut. Also called sep mag.
  • Double-tracking
    Originally, double-tracking meant the recording of a vocal track on one tape recorder track, then listening to this while recording another similar track. The two tracks are combined and re-recorded into a single track, which will sound more diffuse due to slight differences in the two original tracks as double-tracking produces a slight chorus effect to voices. In this case, it is also called re-tracking. Double-tracking can be done with DSP which introduce a small randomly varying time delays to one signal and then combine it with the original signal. See delay(3), stereoizing.
  • Doubling
     If a loudspeaker is driven too hard in its low-frequency range, it will produce second-harmonic distortion, sometimes with greater amplitude than the fundamental. The doubled frequency sounds one octave higher than the fundamental, and is often not musically annoying. This is called frequency doubling, or simply doubling.
  • Downbeat
    See beat.
  • Downmix
    A mix derived from a multichannel (usually 5.1 format) source to create a compatible stereo, mono, or other version of fewer channels. The common use of downmixing today occurs in consumer Dolby Digital products to play back a 5.1-channel DVD mix either via Dolby Pro-Logic decoding or in standard two-channel stereo for headphones. In those instances, an Lt-Rt or an Lo-Ro respectively, are the result.
  • Downtime
    Opposite of uptime. This refers to the amount or percentage of time that a product, system, or service is operational.
  • Downward expander
    See noise reduction.
  • DP5xx encoding
    A family (DP521/DP522/DP523/DP524) of 2-channel codecs used for point-to-point and point-to-multipoint signal distribution: ISDN, Switched-56, T1 or DS-3 networks; recording/post-production studio interconnection with or without video; and voice-over and other applications. AC-2 and AC-3 perceptual coding algorithms are supported to provide audio transfers at a total data rate between 56 kBps and 384 kBps. With AC-3, single-channel, two-channel, and composite stereo algorithms are supported.
  • DRAW
    Digital Read After Write, an erasable CD that can be re-recorded.
  • Drawbar
    On a Hammond organ with tonewheels, a slider that shortens the distance between the axle bearing the wheels and the transducer which converts their spinning patterns into an audio signal. This has the effect of introducing a particular harmonic into the sound to alter its timbre. While similar in purpose to a stop on a pipe organ, it has the advantage of being variable in intensity as opposed to a stop’s simple on/off action. Drawbars have been retained on more recent electronic organs of the Hammond type, but their function is now to act as simple faders that adjust the gain of different oscillators.
  • Drift
     In magnetic tape recording, any extended deviation from the nominal tape speed. Drift can be due to excessive take-up tension, improper capstan motor control, etc.
  • Driver
     (1) A power amplifier which increases the amplitude of a voltage,current, or power signal, (2) any direct radiator speaker, or (3) the term used to describe the chassis loudspeaker, mid-range unit, or tweeter elements of a loudspeaker system (as opposed to speaker system which covers both cabinet and drivers.) (4) A software program which enables communication between a particular make and model of a hardware device and the computer’s operating system, usually necessary for some kind of I/O device such as a soundcard, printer, or scanner. The problem of outdated hard-disks and soundcard drivers is particularly problematic.
  • Drop-frame timecode
    A version of the SMPTE timecode used for color video recording where two frames are dropped at the beginning of each minute, except at the beginning of every tenth minute, devised to compensate for the difference between the NTSC (US) standard of 29.97fps and a real-time counter. The difference equates to 108 frames per hour. To avoid this confusion, most audio-only synchronization applications specify a non-drop time code.
  • Drop-in
    See punch-in.
  • Dropout
    (1) In analog magnetic tape recording, the quality of the recorded signal depends on the uniformity of the magnetic coating of the tape. If its sensitivity varies on the tape, the signal level will be reduced periodically, and these reductions in level are called dropouts, their combined effects resulting in an increased noise level in the reproduced signal. See asperity, calendering. In a digital recording, a dropout is caused by an irrecoverable data error. (2) In timecode, a loss of sequence in the linear timecodetime code count.
  • Drum booth
    An acoustic isolation booth or small room primarily intended as an enclosure for the recording of drums, traps or other percussion instruments and their players. Acoustically sealed off from the main recording space, drum booths have bass traps to prevent loud percussive transients from being heard. Some drum booths are not fully enclosed. This type of booth does not provide complete isolation, but does avoid the small-room problem of standing waves and lower midrange resonances that can give enclosed booths an unnatural, closety sound.
  • Drum pads
     A set of pads which have a similar response to the heads of acoustic drums when struck with sticks. They are made for two purposes: to quiet drum practice, and, when fitted with suitable transducers, to play electronic (usually sampled) drum sounds. If equipped with MIDI, drum pads can also act as a controller, allowing drummers to trigger any type of synthesized sound across a MIDI network.
  • Dry
    Consisting entirely of the original, unprocessed sound. The output of an effects divide is 100% dry when only the input signal is being heard, with none of the effects created by the processor itself. Lacking in reverberation. Compare with wet, flat.
  • Dry/wet balance
    This refers to the amount of dry signal relative to the amount of reverb or other effect-processed wet sound.
  • DS4
     The name of the original Dolby Laboratories recording/monitoring unit used by re-recording stages during a Dolby Stereo mix. Prior to the 2-track print master, the unit is used for 4:2:4 monitoring purposes, encoding a 4-channel composite mix into two tracks and then decoding it back into four channels. Later versions of these units include theSEU4 and SDU4 units which offer, respectively, the ability to encode and decode print masters, although without either the container of the optical track simulation featured in the DS4. The DS10 contains a magneto-optical recorder for theatrical Dolby Digital mixes and also records the Lt-Rt SR-encoded print master. None of the above units can be purchased; their use is free for films that have paid for the appropriate license fee and/or trademark agreement.
  • DS10
    See DS4
  • DSD
    See Direct Stream Digital
  • DSP
    Digital Signal Processor. Broadly speaking, all changes in sound that are produced within a digital audio device, other than changes caused by simple cutting and pasting of sections of a waveform, are created through DSP. A digital reverb is a typical DSP device.
  • DTL
    Direct Time Lock. An early MIDI synchronization system developed by MOTU. See MTC.
  • DTR
    Digital Tape Recorder. This is the analog version. An analog audio tape recorder is called an ATR.
  • DTRS
     A 16-bit format used on Tascam and Sony MDMs, providing up to 108 minutes of 16-bit, 8-track record time on an NTSC-120 Hi-8mm videocasette. See ADAT.
  • DTS Stereo
     See stereo optical print.
  • DTV
    Digital TeleVision. DTV’s audio specification provides up to six discrete channels of 5.1-format audio, where the LFE channel is band-limited to 25Hz-120Hz. DTV has been developed specifically for the home theater market, as an improvement to the ProLogic system.
  • Dual Cone
     Speakers which have two cones; the second cone is usually much smaller and glued directly to the centre of the main cone although it has just one voice coil.
  • Dub
    (1) (verb) In the most general sense, to dub is "to copy," although in film sound it has many similar meanings. Dub can refer to the act of replacing dialog, usually via ADR, either in the original language or in a foreign language. (2) Dubbing is also the common name for re-recording.
  • Dub-A, Dub-B, Dub-C
    See ProDigital.
  • Dub masters
     See final mix.
  • Dubber
     Film sound term for a playback-only mag machine. These were previously known as dummies. See digital dubber.
  • Dubbing
    (1) The act of re-recording sound effects, location sound, music, dialog, and/or Foley. Usually used to refer to the substitution of a foreign language or other replacement for the original dialog track in a film or TV production. (2) The process of making a copy or copies of a recorded analog or digital original. (3) To mix together onto a single track all of the separate edited soundtracksound tracks of a film or television production. See re-recording, dubbing theater and transfer.
  • Dubbing theater
     Also called a dub stage. A special studio where music is blended with dialog and sound effects for the final soundtracksound track. A dubbing theater is actually a small movie theater, with a large screen and full theater surround system. A row of seats is removed from the middle of the theater and a large mixing console specially designed for film sound is put in place. There is also a machine room which houses dubbers and projectors, isolating the noise from the recording studio in which the DME stems can be recorded in sync with film projected on a screen visible through a window. The screen hangs in a theater equipped with the mixing console which controls the sounds played back by all the dubbers, other prerecorded sources, and the sounds being recorded in the studio. The theater itself is designed to approximate the acoustics of a public cinema. Also called mixing studio, re-recording studio, re-recording stage, or theater.
  • Duck
    (verb) To lower the level of music to accommodate dialogue or other sound effects.
  • Dummy load
    A high-power resistor that is connected to the output of a power amplifier to make the amplifier function as though it had a loudspeaker connected to it. A dummy load circuit can be used to test amplifier performance as it would perform when connected to loudspeakers, or in a device such as a speaker simulator so that the amplifier always sees a high-impedance load at the output stage, even if no loudspeaker is connected.
  • Dump edit
    See edit switch.
  • Duo-bilateral
    The technical term for the variable area optical soundtrack format used on all 35mm mono and stereo soundtracks. See SVA, Dolby Stereo, DTS Stereo.
  • Duplet
    A pair of notes (or rests) executed in the time normally taken by three of the same value, most commonly occurring in compound-time music. The inverse of a triplet. See time signature.
  • Duration value
     The duration of a note is strictly a result of the time difference between when a given MIDI Note-On message is recorded and when a Note-Off message with the same note number is recorded. If a duration value is changed, it will result in the change of the time when the Note-Off message is transmitted. If the note start time is modified, both the Note-On and Note-Off times will be moved forward or backward by the same amount.
  • Duty cycle
    In a pulse wave, where immediate transitions occur between the high and low levels, mark is the time in one cycle occupied by the high level, while space is the time in the same cycle occupied by the low level. The ratio of mark to the whole determines the timbre of the sound represented by the saveform. Also called the mark/space ratio. See also pulse wave, square wave, Appendix C.
  • DV format
    DV is the DAT of video, except that unlike DAT, it has become a popular consumer format. These Tapes use 6mm tape in a compact package. The video is compressed by 5 to 1 – the same ratio as minidisk. DV looks fantastic compared to analog domestic formats like VHS. DV is good enough to broadcast, but it would be better used for documentaries rather than professional television programming. It can also be used for anything where the message is more important than the medium. With a good lens and lots of light, DV can give professional video formats a scare.
  • DVD
    Digital Video (Versatile) Disc. A new multiple media format agreed upon by Sony, Philips, Toshiba, and others. DVDs are the same size as a CD, only with a higher track and pit density. The first, single-sided DVDs will hold 4.7Gb; as double-sided, multi-layer discs are available, the capacity will be 8.5Gb and 17Gb, respectively. Transfer rates are about 1.35Mbps, or about as fast as an 8X CD-ROM drive. The data format is 24-bit 96kHz. One DVD is sufficient to store a typical movie, eight tracks of Dolby AC-3 surround audio, and numerous subtitle tracks, which is why the film industry is pushing it: an improvement in the potential of both audio and video quality with the profit profile of a CD. One DVD-5 disc will allow 318 minutes of 48kHz, 20-bit, two-channel audio, or about 144 minutes of 88.2kHz, 24-bit, two-channel audio. At 88.2kHz, 24-bit, LCR plus two channels of 44.1kHz, 20-bit surround-sound, a DVD-5 will hold 75 minutes of audio.
  • DVD
    Digital Video (Versatile) Disc. A new multiple media format agreed upon by Sony, Philips, Toshiba, and others. DVDs are the same size as a CD, only with a higher track and pit density. The first, single-sided DVDs will hold 4.7Gb; as double-sided, multi-layer discs are available, the capacity will be 8.5Gb and 17Gb, respectively. Transfer rates are about 1.35Mbps, or about as fast as an 8X CD-ROM drive. The data format is 24-bit 96kHz. One DVD is sufficient to store a typical movie, eight tracks of Dolby AC-3 surround audio, and numerous subtitle tracks, which is why the film industry is pushing it: an improvement in the potential of both audio and video quality with the profit profile of a CD. One DVD-5 disc will allow 318 minutes of 48kHz, 20-bit, two-channel audio, or about 144 minutes of 88.2kHz, 24-bit, two-channel audio. At 88.2kHz, 24-bit, LCR plus two channels of 44.1kHz, 20-bit surround-sound, a DVD-5 will hold 75 minutes of audio. DVD players will be able to play back CDs, but not those written using the CD-R standard. As with CD-ROM formats, DVD specifications are referred to in terms of books, A-E: Additional DVD subdesignations are:
  • DWDM
    Dense Wave Division Multiplexing. Frequency-domain multiplexing in the optical domain, whereby thousands of digitized streams are imposed on different frequencies or colors of laser light and launched simultaneously down an optical fiber. Frequency-discriminating detectors at the destination sort out each carrier color and decode the date. DWDM is used by telecoms to dramatically increase the payload capacity of in-place fiber.
  • Dynamic allocation
    See dynamic voice allocation.
  • Dynamic effect
    (1) An effect which alters the loudness characteristics of a signal without introducing any timbre changes. The most common dynamic effects are compression and limiting. (2) Some companies use the term dynamic effects to refer to effects devices whose processing parameters can be controlled in real-time via MIDI.
  • Dynamic equalization
    Equalization where the amount of boost or cut varies according to the dynamics and spectral content of the signal being processed. Dynamic equalization is most often used in audio enhancers.
  • Dynamic filter
     (1) An early type of single-ended noise reduction system that uses one or two filters whose rolloff frequencies are controlled by the level of the signal. As the high-frequency signal level falls during soft passages, the high-frequency response is reduced; when the signal level is high, the full bandwidth is restored. (2) A circuit used in aural exciters where a side-chain signal is combined with some dry signal in such a way that the original signal is modified both additively and subtractively to create the impression of an increase in both bass and brightness and the mid-range appears more focused. This type of spectral shaping is designed to be closely related to the way the human hearing system changes at different listening levels. See equal loudness curves.
  • Dynamic headroom
    The ability of a power amplifier to handle short bursts of power without overload.
  • Dynamic loudspeaker
     See loudspeaker.
  • Dynamic microphone
    In a dynamic microphone, a moving coil in a magnetic field is to generate electricity. Two types of dynamic microphones are the moving coil and ribbon. (Moving coil mics are typically referred to as dynamic mics, while ribbon mics seem to be called ribbon mics.) Dynamic mics have a rougher response than condensers or ribbons, and can be used to soften fine detail in the recorded sound. A well-designed moving-coil dynamic mic can handle very loud sound without distortion, and so is preferred for miking guitar amps and drums. Dynamic mics also have a pronounced presence peak that gives the sound an edge or punch.
  • Dynamic range
    (1) The amplitude range of a sound from its softest to its loudest. (2) Also called dynamic-range, the range of sound levels which a system can reproduce without distortion, i.e., the peak signal-to-average noise, or the difference between loudest level the system can reproduce without distortion and the noise floor of the system. See Lmax/Lmin. Desired dynamic range can be defined as the range of signal resolution plus the range of amplitudes of the signals in the program material. For example, if there is a 12-bit signal (72dB) and a range between Lmin and Lmax of 30db, the desired production dynamic range would be 102dB. In terms of recording, headroom plus the S/N ratio equals the dynamic range of the medium. For acoustic spaces, the dynamic range is the range of SPLs between the acoustical noise floor (about 30dB SPL for a quiet recording space) and the onset of nonlinearity in the air (about 130dB SPL). This is about 100dB SPL, approximately the dynamic range of a digital audio recorder, if you count all 16 bits as significant, which, of course, they’re not.
  • Dynamic signal processor
     Any electronic device whose type or degree of operation changes with response to level or other characteristic of the input signal, i.e., with feedback, for example compressors, downward and upward expanders, gates, limiters, NRNR systems, flangers, etc. The opposite of static signal processing.
  • Dynamic voice allocation
     A feature of multitimbral synthesizers where a voice always is made available to sound new notes when all the synth’s polyphonic voices are in use. In the most common scheme, the most recently played note steals the voice from the oldest note currently sounding, or sometimes the lowest amplitude sound. The usual alternative to dynamic allocation is to assign an inflexible, predetermined number of voices per sound. See voice stealing.
  • DYNAS
    New revolutionary technology to guarantee perfect FM reception due to higher selectivity and sensitivity.
  • Early reflections (ER)
     (1) The first and following reflections from adjacent room boundaries, as opposed to later reflections which are produced by farther surfaces or which have taken a longer path to reach the listener. (2) A reverb algorithm whose output consists of a number of closely spaced discrete echoes, designed to mimic the bouncing of sound off of nearby walls in an acoustic space. See ESS
  • Earwig
     A small earpiece micropnone used to give actors an audio reference (frequently a guide music track) so that their live audio can be recorded live. See also thumper, IEM.
  • EASI
    enhanced audio streaming interface. Emagic’s multi-channel alternative to stack multimedia audio drivers. EASI provides a direct and consistent way for audio software and hardware to communicate, resulting in improved audio timing and reduced latency.
  • Eastman Kodak negative (EK neg)
     Film laboratory colloquialism for "original camera negative." Used in film production to describe a release print made from the original negative, whether or not any of the film involved was actually made by Kodak, Inc. Also called an OCN, probably for Original Color Negative.
  • Echo
    An audio effect which is a discrete (where the onset of the repeated sound is distinct) repetition of a sound arriving at least 50ms after the incident sound, as opposed to reverberation, which is a continuous wash of closely spaced, non-discrete, echoing sound. See delay(3).
  • Edge
     A subjective impression of a certain roughness in the reproduced sound of a musical instrument. It is usually caused by non-uniform, high-frequency response in the loudspeaker or other audio device.
  • Edge track
     (1) In multitrack recording, either of the recorded tracks located along the edge of the tape. (2) The U.S. standard position of the recorded track on 16mm magnetic film, i.e., the position along the edge opposite the sprocket holes. See film soundtrack.
  • Edgecode
     Inked numbers applied outside the sprocket holes on file prints and mag film, used for synchronization reference. See Acmade, preview codes.
  • Edit controller
    See edit programmer.
  • edit decision list (EDL)
     Prior to editing a master recording or motion picture, the various takes are auditioned and a list of the desired ones is created, along with notes telling exactly where the cuts are to be made. The resulting document is the EDL. This consists of the list of SMPTE time code in feet/frames, including instructions for fades, dissolves, and other special effects--corresponding to all the segments that the editor of a videotape production has decided to use in the final cut. The EDL is usually computer-generated. See also playlist.
  • Edit master
    Video industry term for the tape containing the finished (edited) program.
  • Edit mode
    See cue mode.
  • Edit programmer
     A computer used to perform on-line edits and auto-assemblies. The video editor enters the EDL, a sequence of SMPTE timecode time codes corresponding to the shots and specific frames to be connected. The edit programmer then controls the video playback and re-recording decks to produce the edited video master tape according to the editor’s instructions. Depending on the sophistication of the specific unit used, the editor may have to perform some special effects manually, on prompts given by the edit programmer. Also called an edit controller
  • Edit switch
    On a tape recorder, a switch that engages the play mode but not the take-up motor. Tape is driven past the playback head and reproduced, but then spills off the machine and may be edited out. This process is called a dump edit. On some machines, the edit switch merely defeats the tape lifters, allowing the editor to scrub the tape past the playback head.
  • Edit switch
    On a tape recorder, a switch that engages the play mode but not the take-up motor. Tape is driven past the playback head and reproduced, but then spills off the machine and may be edited out. This process is called a dump edit. On some machines, the edit switch merely defeats the tape lifters, allowing the editor to scrub the tape past the playback head.
  • Editing
    Intercutting, slicing and arrangement of several analog tapes or digital data recordings of audio or film take in order to make an improved performance.
  • Editing block
     A cast metal block with a channel that holds magnetic tape firmly and in a straight line. Diagonal slits through this channel allow a razor blade to make precisely angled cuts in pieces of tape, so that two separate pieces aligned in the channel may be spliced together. The resulting splice, if properly made, will be inaudible as it passes over the playback head of the recorder.
  • Editor / librarian
    : A piece of computer software that allows the user to load and store patches and banks of patches (the librarian) and edit patch parameters (the editor) by patch name.
  • Editorial sync
    Alignment of picture and soundtracksound tracks such that their start marks are equal numbers of frames prior to the first frames of picture and sound, respectively. See projection sync.
  • Effect send level
    The amount of effect to be added, such as reverb, chorusing, or other enhancements, to each channel.
  • Effects
    Abbreviated FX. Any form of audio signal processing or a device to produce: reverb, delay, chorusing, echo, flanging, and phasing, rotary (Leslie) speaker simulation, distortion, and tremolo, etc. See processor.
  • Effects control
    Two classes of Controller Change messages which are used to introduce and adjust some kind of effect such as reverb.
  • Effects control 1 & 2
    Controller Change messages which are intended to be assignable to parameters (other than depth) which appear in a synthesizer or effects unit and which control some aspect of an effect such as reverb time or pitch-shift. They operate in conjunction with Effects Depth messages; the two message types taken together are called Effects Control.
  • Effects depth
    : (1) A parameter on a synthesizer, effects unit, etc. which can be adjusted by the user to alter the mount of a particular effect, such as reverb, delay, or chorus. (2) Effects Depth controllers. Controller Change messages which are used to implement the function described in Effects Depth. These were initially assigned to specific effects, but are now generalized and operate in conjunction with Effects Controls 1 & 2 messages; the two message types taken together are called Effects Control.
  • Effects loop
     A mixing console circuit that is used to add an effect to a signal or a group of signals. When the effect unit is plugged into the effects send bus circuit (via the effects send and effects return jacks), it literally functions as a loop, splitting the signal off from the mixer and sending it to the effect, then returning it to the mixer, where it is combined with the original signal.
  • Effects master
     See effects send.
  • Effects return
    An input on a mixing console that receives the wet signal from the effects devices. The effects return inputs usually have volume controls (faders) to control the intensity of the particular effect in use.
  • Effects send
    An output from a mixering console that is connected to the input of an effects device. The effects send outputs usually have volume controls to set the effect send level, and the overall level of all the effects send outputs may be controlled by an effects master control operating from the effects bus. Effects sends (usually referred to in this case as aux sends) are typically used to feed effects processors such as reverbs, or are used to feed monitor systems, either speakers on stage or headphones in the studio. Whereas the main outputs of a mixer have a mix of everything that has a main fader turned up, the effects sends, with their own mix controls, have an independent mix. Effects sends are also used to feed the house mix to the PA system, when they are usually called post-fader sends. Also called an post-fader send, or aux (auxiliary) send. See insert send.
  • Effects send bus
    The mixing bus in a recording console used to mix the signal to be sent to the various effects devices. Also called the effects send bus.
  • Effects track
     (1) An edited track of magnetic film containing sounds other than dialog or music. There can be many effects prepared for a film mix. (2) In videotape productions whose sound is assembled on a multitrack tape, the track or tracks on which sound effects are recorded. (3) In the 35mm three-track mix of a motion picture, the recorded track that contains sounds mixed from all the effects tracks. See film soundtrack.
  • Efficiency
     A measure, usually applied to loudspeakers, of how much of the input electrical energy is converted to sound energy, expressed in percent. The remaining energy is converted into heat.
  • EIAJ
    Electronic Industries Association of Japan.
  • EIDE
    See IDE.
  • Eigentone
     See standing wave.
  • Eight-to-Fourteen Modulation (EFM)
      The data encoding scheme used in CDs in order to optimize the process of reading off the disk. Groups of eight data bits are regrouped into fourteen-bit blocks by EFM modulator during cutting of the CD master, permitting about 25% greater data density to be laser-inscribed on the disc and allowing easier error recognition. An EFM demodulator in the CD player decodes the data.
  • Electret
    If two metal plates have molten wax poured between them and a high DC voltage is sent across the two plates, this assembly yields a permanent electric field, in the same way that a magnet produces a permanent magnetic field. It is hypothesized that the polar molecules in the wax align, producing the electric field. An assembly of this type is used to provide a polarization voltage for small condenser microphones so that they do not require phantom power at 48V, but operate instead at a small pre-amplified voltage of 5V-12V. Microphones constructed in this way are called electret microphones.
  • Electro-magnetic compatibility
    Audio equipment that is designed to be immune to EMI is said to be electro-magnetically compatible. Shielding is one EMI technique, as is line-filtering, etc.
  • Electro-magnetic (EM)
    The name for interactions between electrical and magnetic phenomena. The science of electromagnetics deals with the application of electrical principles and apparatus to magnetic phenomena. Transformers, antennæ, and phonograph cartridges are electromagneticelectro-magnetic devices. Longer explanation: There are four known forces operating in the universe: strong and weak nuclear forces, gravity, and electromagnetism, the latter two being the two manifestations of electromagneticelectro-magnetic force. These are mutually affective, i.e., a magnetic field can influence an electric field and vice versa as an electromagneticelectro-magnetic wave consists of both an electric field and a related perpendicular magnetic field. The electromagneticelectro-magnetic spectrum consists of (in order of increasing frequency) radio waves, microwaves, infrared light (heat), visible light, UV light, X-rays and gamma rays. All electromagneticelectro-magnetic waves propagate at the same speed, the speed of light.
  • Electro-magnetic pick-up
    See piezo pick-up, DI.
  • Electroacoustic
     The name for interactions between electrical and acoustic phenomena. The science of electroacoustics deals with the application of electrical principles and apparatus to acoustical phenomena. Transducers, such as microphones and loudspeakers, are electroacoustic devices.
  • Electroacoustic transducer
     A device which converts sound waves to electrical signals. Transducers such as microphones, loudspeakers, and phonograph cartridges are electroacoustical devices. The primary problem with electroacoustic transducers is that they do not exhibit a linear frequency response except for a relatively small range of signal frequency and amplitude. See DI.
  • Electronic feedback
     See feedback.
  • Electrostatic loudspeaker
    A dipole speaker with a transducer that uses the audio signal to vary the strength of an electric field which, in turn, induces vibration in a metallic or metalized membrane. In principle, it is the reverse of an electrostatic microphone, and very different from the more common electromagneticelectro-magnetic voice coil arrangement. Used for consumer equipment as the power output is low. Electrostatic speakers are usually quite large, such as 6’ high by 2’ or 3’ wide. They are always direct radiators, and they must be large to attain reasonable efficiency at low frequencies. The radiation pattern of an electrostatic speaker in a free-field is similar to that of a figure-eight microphone. Because of their large size, electrostatic loudspeakers tend to become very directional in the high-frequency range. They are also characterized by a low impedance, and this is problematic for some amplifiers. See also planar loudspeaker.
  • Electrostatic microphone
    A class of microphone, of which condenser and electret are types, in which air pressure changes cause changes in the capacitance of a condenser. The capacitor is normally biased by a voltage which is supplied from batteries or via phantom power from the signal cable. The electret is an exception, as this requires such a small biasing voltage that it is possible to charge it permanently at the time of manufacture; Sennheiser mics use a proprietary biasing scheme which utilizes RF instead of a DC voltage.
  • Electrostatic noise
    A field of random electrical charges that can affect an audio line. Electrostatic noise can be generated by neon or fluorescent lighting, electrical motors, and other broad-spectrum emissions sources. Electrostatic noise is the electrical field which is generated by EMI.
  • Elliptical equalizer
    A special equalizer which causes the two channels of a stereo signal to be more nearly in phase at low frequencies, making the signal easier to cut into a record (an LP stylus has an elliptical cross-section).
  • Elliptical filter
    : A multiple-element, lowpass or bandpass filter which has the steepest possible rolloff slope and a small amount of ripple in the passband, with one or more notch filters added to it. Elliptical filters are used as anti-aliasing filters in digital audio devices.
  • EMI
    Electro-magnetic Interference. Stray electro-magnetic fields generated from any current-carrying conductor such as nearby motors, switching controllers, high-power contactors, etc. which cause a brief, intense pulse that often couples into low-level signal circuits causing noise. This interference can enter either directly into the signal path, or indirectly via the power or ground connection. High-power RF transmitters can cause similar effects, called RFI. See induction.
  • Emphasis
    See resonance 
  • Encoding
     (1) The process of converting the already sampled, numerical voltage of the analog input into binary numbers and assembling these with any location and error-related data generated elsewhere into complete digital words, usually of 16 bits. See analog-to-digital converter. (2) The application of any type of processing to a signal before recording which will later be removed by complementary processing during playback. Most NR systems are good examples of the encoding/decoding process. See stretched.
  • Encryption
    Converting information form an open form to a closed secret form requiring hidden knowledge to convert the data back into the open form.
  • End-addressed
     A microphone that is aimed at the sound source, as opposed to side-addressed, which is aimed with the side of the mic at the sound source.
  • Enhanced CD
    A multisession CD format which allows Red Book, Yellow Book and Blue Book CD data to be stored on one disc.
  • Envelope
    The shape of the amplitude vs. time graph of a musical sound; the shape of a sound as it changes over time. The shape of a synthesizer’s envelope is controlled by a set of rate (or time) and level parameters. The envelope is a control signal that can be applied to various aspects of a synthesizer’s sound, such as pitch, filter rolloff frequency, and overall amplitude. Usually, each note has its own envelope(s).
  • Envelope follower
     A device used in electronic music synthesis that converts the envelope of a musical signal into a control voltage. That is, the output voltage will be low when the signal is soft and high when the signal is loud. The control voltage can then be used to control any number of parameters in the synthesizer.
  • Envelope generator
    A hardware device or software routine that generates a sound envelope. Also known as a contour generator or transient generator because the envelope is a contour (shape) that is used to create some of the transient (changing) characteristics of the sound over time. The purpose of an envelope generator is to give a shape to each note. By itself, an envelope generator makes no sound. Its output is used as a control source that tells some other part of the synthesizer what to do. Typical synths have three envelope generators for each oscillator: one to control pitch, one to control the filter rolloff, and one to control amplitude. See ADSR
  • Envelope generator
     A hardware device or software routine that generates a sound envelope. Also known as a contour generator or transient generator because the envelope is a contour (shape) that is used to create some of the transient (changing) characteristics of the sound over time. The purpose of an envelope generator is to give a shape to each note. By itself, an envelope generator makes no sound. Its output is used as a control source that tells some other part of the synthesizer what to do. Typical synths have three envelope generators for each oscillator: one to control pitch, one to control the filter rolloff, and one to control amplitude. See ADSR.
  • Envelope tracking
    A function that changes the length of one or more envelope segments depending on which key on the keyboard is being played. Envelope tracking is most often used to give higher notes shorter envelopes and the lower notes longer envelopes, mimicking the response characteristics of percussion-activated acoustic instruments. Also called keyboard tracking, key follow, and keyboard rate scaling. See ADSR.
  • EON
     Enhanced other networks. Allows interruption of RDS bulletins from other local stations.
  • EOX
     End Of eXclusive. A System-Common MIDI message used as a flag in a MIDI datastream to indicate the end of a System-Exclusive message transmission.
  • EP
     Extended Play. A type of 7" phonograph record, usually played at 33 rpm, allowing two songs to be cut on each side for a total recording time of up to 7 minutes. Also a 10" or 12" album with between three and seven songs. EPs are intended to sell at less than album prices and are a way of establishing new artists without requiring record buyers to pay full LP prices. (2) Also, Executive Producer.
  • Equal loudness curves
    Also known as Fletcher-Munson curves or phon lines. Equal loudness curves are the inverse of frequency response curves and reflect the phenomenon that humans do not hear all frequencies as having equal loudness. In other words, human hearing is not liner in frequency. This is particularly problematic in recording as a mixed master will be perceived differently depending on the playback level. Specifically, there is a marked drop-off in aural sensitivity at low frequencies. At the opposite extreme, humans have high sensitivity to sounds in the 1kHz-8kHz range, with sound again dropping away above 12kHz. Also called equal loudness contours. In the graph below, note that at 60dB SPL, a 1kHz tone is perceived as of equal loudness as a 20Hz tone at over 100dB SPL. At low levels, these differences are accentuated: the same 1kHz tone at 10dB SPL requires 80dB SPL at 20Hz.
  • Equal-tempered
     A system of tuning in which the diatonic comma is divided equally between the twelve half-steps of the octave. All the half-steps are equal in size and are exactly one-twelfth of an octave, spanning a frequency ratio of : , or about 6%, or 1:1.059. In equal temperament, all the intervals are the same regardless of the key in which one is playing, and none except the octave is perfectly tuned. This makes it very easy to modulate from one key to another, although the keys lose their individuality because they all have equal intervals. The result is that the fourth and fifths are within 0.001% of just intervals, however the thirds are about 0.01% away from pure thirds which produce audible beats, the thirds in all keys being equally bad. See temperament, syntonic comma, diatonic comma.
  • Equalization curve
    In tape recording and playback, a standardized equalization effect applied to an audio signal. Pre-emphasis and the complementary de-emphasis curve is applied to the recorded and reproduced signal, respectively. Pre- and post- equalization curves are different for each standard tape speed, and standards are given by the various organizations such as NAB, CCIR, and IES for their respective countries. Also described as a pre-emphasis curve and de-emphasis or post-emphasis curve. See also RIAA curve.
  • Equalization (EQ)
    An effect that allows the frequency-selective manipulation of a signal’s amplitude. The simplest equalizers are shelving types, offering the ability to cut or boost gain above or below a given frequency. Equalization doesn’t only change the level of specific parts of the audio spectrum, it also changes the phase of the affected frequencies relative to those that aren’t being EQ’d, i.e., EQ affects both the frequency response and phase relationships of the signal. See composite equalization, pre-emphasis, room equalization.
  • Equalizer
     An adjustable audio filter inserted in a circuit to divide and adjust its frequency response, altering or distorting the relative amplitude of certain frequency ranges of an audio signal. The effects processor used for equalization. Equalizers come in two varieties, graphic and parametric. A graphic equalizer typically has a number of fixed-frequency bands (5-10 in consumer equipment, 31 in professional equipment), each wired to its own front-panel slider. The control is over the amount of cut or boost (in dB) at each band. A parametric equalizer goes two steps further: the center frequency of each band can be selected by the user, as can the bandwidth. This affords more precise control over which frequencies will be affected by the boost or cut in amplitude. Because EQ circuitry with these controls is more expensive to build, a parametric equalizer will typically provide fewer bands than a graphic equalizer. A semi-parametric equalizer, sometimes found in multieffects devices, provides control over the center frequency of each band, but not over the bandwidth. See also active equalizer, passive equalizer, shelving equalizer, Q.
  • Equalizer
     An adjustable audio filter inserted in a circuit to divide and adjust its frequency response, altering or distorting the relative amplitude of certain frequency ranges of an audio signal. The effects processor used for equalization. Equalizers come in two varieties, graphic and parametric. A graphic equalizer typically has a number of fixed-frequency bands (5-10 in consumer equipment, 31 in professional equipment), each wired to its own front-panel slider. The control is over the amount of cut or boost (in dB) at each band. A parametric equalizer goes two steps further: the center frequency of each band can be selected by the user, as can the bandwidth. This affords more precise control over which frequencies will be affected by the boost or cut in amplitude. Because EQ circuitry with these controls is more expensive to build, a parametric equalizer will typically provide fewer bands than a graphic equalizer. A semi-parametric equalizer, sometimes found in multieffects devices, provides control over the center frequency of each band, but not over the bandwidth. See also active equalizer, passive equalizer, shelving equalizer, Q.
  • Equivalent input noise (EIN)
     EIN is becomming a common method for specifying noise in audio equipment. This is a computed figure equal to the noise measued at some gain setting, minus the gain. For example, if a microphone preamplifier puts out -85dBV noise when set for 40dB of gain, the EIN is -125dBV. Note that, while -125dBV seems better than -85dBV, both figures represent the same amount of noise.
  • Erase frequency
    See erase head
  • Erase head
     The head on a tape recorder that erases magnetic information on the tape, located just before the record head in the tape path. A high-level, high-frequency (150-300kHz) tone, called an erase frequency which, when fed through the erase head, re-randomizes the orientation of the tape’s magnetic domains so that the signal to be recorded will have no hysteresis. See erase oscillator.
  • Erase oscillator
     A very high-frequency oscillator built into a tape recorder to supply current to the erase head. In most machines, the same oscillator supplies the bias and erase frequency.
  • Error concealment
    A technique to reduce the audible effect of a digital error in a digital audio system when the error cannot be corrected by the techniques of digital error correction. Error concealment usually consists of making a smooth transition from the last good data block before the error to the first good data block after the error, usually in some form of interpolation, i.e., crossfading. Error concealment is the reason that a digital copy from one source is often not an exact clone of the digital master. When duplicating a digital master, error correction and error concealment algorithms must be thoroughly understood and the dubs checked for reproduction quality. See error protection.
  • Error correction (ECC)
     Error Correcting Code. In digital audio systems, the sampled amplitudes of the signal waveform are expressed by digital encoding. If, in the transmission of the digital words, some bits are missing or incorrect due to tape dropouts, etc., the result will be gross distortion of that portion of the signal when it is reconstructed. Error correction is made possible through the use of a parity check bit added to each data word, as well as more complex schemes. See error concealment, error protection, CRC.
  • Error correction (ECC)
     Error Correcting Code. In digital audio systems, the sampled amplitudes of the signal waveform are expressed by digital encoding. If, in the transmission of the digital words, some bits are missing or incorrect due to tape dropouts, etc., the result will be gross distortion of that portion of the signal when it is reconstructed. Error correction is made possible through the use of a parity check bit added to each data word, as well as more complex schemes. See error concealment, error protection, CRC.
  • Error detection
     In digital playback, the use of error bits and data derived from the audio samples to check the completeness and accuracy of the audio data before passing it on to the D/A. See error protection.
  • Error protection
    All of the circuits and data handling procedures that together accomplish error detection, error concealment, and/or error correction functions in any digital recording and playback format.
  • ESS
    Early Sound Scattering. A design for control rooms where the characteristic reflections are so uniformly random that they have no character to impose on the listening space. An ESS control room is one which features a highly diffusive front end (including the monitor walls) which scatters the early sound using Schroeder-type diffusers. The body of the room is absorbent, with most of the lows damped by membrane panels. These rooms can be made fairly live compared to older control rooms, with a flat frequency response and good stereo imaging, both of which remain stable right to the rear corners of the room. As compared with LEDE and RFZ designs.
  • ESS
    Early Sound Scattering. A design for control rooms where the characteristic reflections are so uniformly random that they have no character to impose on the listening space. An ESS control room is one which features a highly diffusive front end (including the monitor walls) which scatters the early sound using Schroeder-type diffusers. The body of the room is absorbent, with most of the lows damped by membrane panels. These rooms can be made fairly live compared to older control rooms, with a flat frequency response and good stereo imaging, both of which remain stable right to the rear corners of the room. As compared with LEDE and RFZ designs.
  • Essence
    In a digital stream of file, essence is the portion of the data that contains the ‘raw’ or basic information of interest, excluding metadata and framing.
  • Esultant tone
     See difference tone
  • Ethernet
     A LAN method first described in 1973, which has become as ubiquitous and adaptable as computers themselves. A “broadcast computer communications network” originally invented at Xerox PARC by Bob Metcalfe and his team, Ethernet has managed to prosper and evolve during a 30-year lifespan, an eternity by any measure of computer technology.
  • Event editing
    See step input.
  • Exabyte
     a company and a family of tape based storage products manufactured by that company.
  • Exciter
    A device for artificially enhancing a signal by adding new partials to it. These devices are said to compensate for loss of high frequencies in analog tape recordings. Also called an aural exciter.
  • Executable
    A binary (only machine-readable) file containing a program that can be ran or executed by a computer
  • Expander
     (1) A signal processing device which is the inverse of a compressor, providing the gradual attenuation of signals that fall below a user-defined threshold. This process, known as expansion, reduces background noise and at the same time increases the dynamic range of the input signal. (2) A synth, with out a keyboard or other master controller, often rack-mounted. Also called a tone module.
  • Expansion
    See expander(1).
  • Expansion ratio
     In an expander that is working below its threshold, the ratio given by the number of dBs change in input over the number of dBs change in output. Typical ratios are in the range 1:2 or even 1:20. Expansion ratio is the opposite and complement of compression ratio.
  • Expression
     One of the defined MIDI Controller Change messages, usually assignable to some parameter in a synthesizer, such as Volume or Filter Cut Off.
  • Extension
    Files used by Mac computer application programs to provide additional functionality to the computer’s operating system. The equivalent of a DLL (Dynamic Link Library) file on a PC.
  • Extension
     Files used by Mac computer application programs to provide additional functionality to the computer’s operating system. The equivalent of a DLL (Dynamic Link Library) file on a PC.
  • Extension
    Files used by Mac computer application programs to provide additional functionality to the computer’s operating system. The equivalent of a DLL (Dynamic Link Library) file on a PC.
  • Extinction frequency
    : In magnetic tape recording, the high frequency beyond which significant cancellation occurs because its wavelength on tape, at the specified tape speed, approaches the width of the head gap.
  • F1
    See PCM-F1
  • Fabric
     A fabric is a collection of host or target channel adapters, links and switches that are cross connected in a many-to-many scheme rather than individual, isolated point-to-point or loop topologies. In the world of fiber Channel networks, fabrics describe the physical interconnection of multiple devices interwoven or connected via hubs, switches or HBAs (Host bus adapters).
  • Fade
    (1) Slow alteration of the level of a signal, usually using a potentiometer. See fade-in/fade-out. (2) Of a piece of music, usually commercial music, the repeated section at the end of the song which is subjected to a gradual fade-out. See also outro. (3) Short for fade-in/fade-out. Optical effects in which a scene is printed with exposure increasing or decreasing to blackness for fade-in and fade-out, respectively.
  • Fade-in / fade-out
     A feature of most audio editing software that allows the user to apply gradual amplitude increase or decrease over some segment of the sound. Fade-in starts with no signal and gradually increases the level. Fade-out starts with a signal present and gradually decreases the level, normally to silence. See crossfade.
  • Fader
     (1) A variable attenuator, or volume control. (2) A variable control used to change the distribution of power between front and rear speakers.
  • Far-field
     If a sound source is operating in an enclosed space, the SPL will vary with the distance that the measuring microphone is from the source. At certain close ranges, the levels will obey the inverse square law and at these distances, there will exist approximately a free-field. At greater distances, the reduction in measured level with increased distance will be less than predicted by the inverse square, and finally a region will be reached where the level is almost constant regardless of the distance, and this is called the reverberant field. The area between the free-field and the reverberant field is called the far-field. Its extent is a characteristic of the directionality of the sound source as well as of the acoustics of the room.
  • FASA
    Frequency, Amplitude, Spectrum, and Ambience. An audio production method which is based on the criteria that can be changed in sonic terms to enhance a recording: Frequency: Pitch, transposing parts, chord inversions, layering with other octaves. Amplitude: Level, use of dynamic range to cut and boost sections, and relative volumes among parts. Spectrum: Textures and the range of frequencies present, layering sounds with others, introducing new textures from other parts, changing the sounds for a part, like playing a percussion line as a bass part, the contrast in frequency and textures used. Ambience: Space, reverb, and image information such as panning, depth, height, forward or recessed, for each part playing.
  • Faulkner array
    A near-coincident microphone configuration which uses a pair of figure-eight microphones, both facing directly forward, but separated by about 8".
  • FC
    Fibre channel. A networked storage center designed to provide high availability performance and scalable storage with reliable Qos and unified management. Due to industry in fighting and lack of standardization, FC is being supplanted by other less-expensive networked storage standards.
  • FCIP
    Fibre Channel (over) IP. A method of encapsulation or “tunneling" FC protocols so that they can be transported over an IP-based network. FCIP allows FC based storage networks to be extended form LAN to MAN and WAN distances.
  • Feed
     In signal routing, an output from one device that is sent into another.
  • Feed reel
     The input reel on a tape recorder, from which audio or video tape is fed to the head stack and onto the take-up reel.
  • Feedback
     There are two types of audio feedback: acoustic and electronic. (1) Acoustic feedback is where a gain control is set too high in a sound reinforcement system and the amplified sound enters the microphone and is reamplified until a steady howl or whistle is heard. This is also called regeneration. (2) Electronic feedback (or negative feedback) involves the application of a small portion of the output voltage of an amplifier to the input so as to cancel part of the input signal, reducing the gain of the amplifier, but also reducing the distortion and noise introduced by the amplifier. See bootstrap. (3) A specific application of feedback in FM synthesis, where at least one operator in each algorithm is equipped with a feedback loop.
  • Feet / Frames
    Footage numbers for film, either separated by a colon or by a "plus" sign. For example, 101:16 and 0101+16 both indicate a point 101 feet and 16 frames into the film. There are 16 frames per foot of 35mm film, and 40 frames per foot of 16mm film. See SMPTE timecode, LFOP, ABS.
  • FFT analyzer
    A digital device which performs the transformation from the time domain to the frequency domain of a sound spectrum over a wide frequency range and dynamic range. It is used to measure distortion, S/N ratio, flutter and wow, as well as the phase response and frequency response of audio devices. See Fourier analysis.
  • Fidelity
     The accuracy with which a music reproduction system will recreate the sound of the original music.v field
  • Field
    (1) The subjective environment which a listener perceives while listening to sound, such as a stereo field. See stereophonic, ambisonic. (2) The area around one or more microphones; the acceptance angle of the microphone. (3) The spatial area of electromagnetic force. (4) In video, a subgroup of visual data consisting of either the odd- or even-numbered lines of any frame. In NTSC, for example, each field is displayed separately for of a second within the total frame duration of second. For each frame, field number one contains line #1, #3...#525; field number two contains lines #2, #4...#524. PAL television broadcasts use an analogous scheme, but has a different frame rate and number of lines per frame.
  • Field rate
    Frequency at which video fields occur: 59.94Hz in NTSC, 50Hz in PAL.
  • Fifth
    The interval between a note and the seven half-steps above or below it. See interval.
  • Figure-eight microphone
    A directional microphone whose pick-up pattern resembles the figure 8, meaning that it is insensitive to the sides but has full sensitivity at the front and back. As the polar pattern resembles the shape of a cosine curve, the figure-eight microphone is sometimes also called a cosine microphone. Figure-eight mics were traditionally ribbon mics, but now they can also be condenser mics. Also called a bi-directional microphone. Figure 8 polar pattern
  • Figure-eight microphone
     A directional microphone whose pick-up pattern resembles the figure 8, meaning that it is insensitive to the sides but has full sensitivity at the front and back. As the polar pattern resembles the shape of a cosine curve, the figure-eight microphone is sometimes also called a cosine microphone. Figure-eight mics were traditionally ribbon mics, but now they can also be condenser mics. Also called a bi-directional microphone.
  • File format
    The data in a computer file has a particular order and length. The specification which determines the structure of the file is called the file format and is software- and/or hardware-specific. Files, such as MIDI files, may contain data, instructions to other software programs and/or hardware devices, and/or programs. The file may also contain ECC data, network information, and other non-user overhead data. Some file formats are made publicly available to allow the implementation of plug-ins; others are proprietary to the vendor. The file format usually begins with a file header, followed by data, followed by ECC data, followed by some kind of stop bit, if the file format is variable-length. See AIFF, RIFF, AU, MPEG, MOD, RA, SFI, SMF, SMP, SND, WAV, HFS, ISO 9660, VOC.
  • File Level
     The ability to only read and modify an entire file and not the underlying protocols that address the storage device on which the file resides. The term “file level" is often used to differentiate “file-level” NASs from “block-level” SANs.
  • Fill
    The sound between words in a production track that is used both to replace undesirable noise on the track and to create handles for use in extending the track at the beginning and the end.
  • Fill leader
     The film that is inserted into units of mag film in order to keep synchronization during silent sections. Fill leader is usually made up of recycled release prints. See also leader, plastic leader.
  • Filled
     Filled effects is a version of the effects stem(s) of a soundtrack which includes all effects, including cut effects and Foley. See M&E.
  • Film
    Now, 35mm film accommodates the 6-track digital sound, but previously almost all films released in 70mm from 1971-1992 which were originally photographed in 35mm and then blown up to the 70mm format specifically for playback with 6-track sound. The motion picture exhibition format from 1955-1971, 70mm, contained 6-track magnetic sound, using camera equipment manufactured by Todd-AO and Panavision. The camera negative was 65mm wide, with the additional 5mm outside the sprocket holes used for the magnetic stripes on release prints. Almost all modern 70mm prints in the U.S. have no magnetic track, but instead use DTS in conjunction with a wide timecode track outside of the perforations.
  • Film chain
    A device consisting of a motion picture projector and video camera, used to copy films onto videotape or to broadcast them directly. To adapt the 24 fps U.S. frame rate to the 30 fps NTSC video frame-rate, some chains use a projector with a five-bladed shutter, which shows each frame of film five times onto the vidicon tube of the video camera. The resulting 120 fps are regrouped four-at-a-time into 30 video images per second.
  • Film footage
    There are 16 fps per foot of a standard 35mm film image, each lasting four sprocket holes. At the standard rate of 24 fps, 35mm film runs at 90 feet per minute, or 18 inches per second. See frame.
  • Film soundtrack
    The audio component, including DME, of a film composition. There is usually a requirement for sound to be synchronized to the video image. This has been achieved by a variety of means, including the recording of sound on optical tracks etched into the film emulsion alongside the frames, fixing magnetic tracks on the film surface, synchronizing the film with a separate tape machine by means of mechanical sprockets, and electronic sync using systems such as SMPTE. See also Dolby Stereo, LC Concept, SR.D, pilot tone, layback recorder, source track.
  • Filter
     (1) A type of equalizing device for subtractively eliminating (subtractively) selected frequencies from the sound spectrum of a signal and perhaps, in the case of a resonant filter, increasing the level of other frequencies. See VCF. For example, a lowpass filter passes lower frequencies and removes the higher frequencies. By raising or lowering the filter rolloff frequency parameter, a sound will be made brighter or darker. (2) A device or MIDI software filter that eliminates selected messages from the MIDI data stream, usually called MIDI filtering by data thinning. See also running status.
  • Filter resonance
    The greater the resonance on a filter, the greater the effect of the filter: as resonance control is turned up, a little peak appears at the rolloff frequency. The harmonics that fall within that peak are accentuated. The greater the resonance, the higher the peak and the more pronounced is this effect. The effect of the swept resonant peak does not occur in real instruments. See also Q.
  • Filter scaling
    See keyboard scaling.
  • Filter, to Filter
    Data processing to remove or ignore unwanted information.
  • Final mix
    The mixing of the final stems, which, when mixed and replayed represent the film’s finished soundtrack. In a stereo film (or surround-encoded TV programming) it is most common to record the DME stems on three pieces of 4- or 6-track magnetic film, with Dolby-SR noise reduction, or on analog or digital multitrack tape, or onto a digital dubber. These stems, also known as dub masters, are then used to create the print masters, the M&E mix, a mono mix, and possibly an airline version. For a non-surround-encoded stereo mix, then the stems might be in standard stereo format, but this precludes the subsequent production of a 5.1 mix, say for DTV.
  • Final mix
    The mixing of the final stems, which, when mixed and replayed represent the film’s finished soundtrack. In a stereo film (or surround-encoded TV programming) it is most common to record the DME stems on three pieces of 4- or 6-track magnetic film, with Dolby-SR noise reduction, or on analog or digital multitrack tape, or onto a digital dubber. These stems, also known as dub masters, are then used to create the print masters, the M&E mix, a mono mix, and possibly an airline version. For a non-surround-encoded stereo mix, then the stems might be in standard stereo format, but this precludes the subsequent production of a 5.1 mix, say for DTV.
  • Finder
     The user interface of the Mac operating system, allowing access to the file system, peripherals, and other components of the system hardware and software.
  • Fine
     The End.
  • Fine cut
    A stage in the editing of a film or video production at which the workprint or EDL is completed, denoting that the production is ready for final cut approval.
  • FIR
    Finite Impulse Response: A class of filter designs whose impulse response falls to zero in a predictable, finite length of time, as opposed to an IIR (Infinite Impulse Response) design whose impulse response may never fully attenuate the impulse. A common use of FIR is to produce filters with a linear phase response. Filters such as analog anti-aliasing filters which have a very sharp rolloff slope produce unacceptable amounts of phase distortion in the output signal; FIR filters are used at the end of an oversampling A/D chain to eliminate any signal that would represent aliasing in the slower output datastream, without causing significant phase distortion.
  • FireWire
    A digital audio transmission medium developed by Apple computer, designed to support dozens, possibly hundreds, of high-bandwidth audio streams. IEEE 1394 is designed to replace point-to-point AES/EBU connections, will support multiple data formats so that audio, video, MIDI, and control signals may all be sent over a single cable. FireWire also distributes power as well as data, permitting hot-plugging of devices. IEEE 1394 is designed to be a fully specified bus, bi-directional and with the ability to broadcast from a single source to multiple receivers. Currently (late 1998) there is a 4.5-limit between any two adjacent nodes, designed to support a simple, low-cost clocking mechanism to be built into the standard to support isochronous data transfers for audio and video. The isochronous clock embedded within the IEEE 1394 standard runs at 8MHz, or one "tick" every 125µs. This is problematic for audio signals which require upwards of 44MHz clock rates, so the FireWire standard is being modified to address the problem of high-resolution synchronization. The signal can traverse up to a maximum of 16 hops, effectively extending the distance to about 70 meters. This was originally developed to support the transfer of high-bandwidth signals between computer peripherals; the multi-layer IEEE 1394 standard also allows the use of many other cabling technologies, including Category 5 twisted pair copper wire and 50mm multi-mode optical fibre, the later permitting distances between devices of hundreds of meters. See also mLan.
  • Fishing rod
    See boom.
  • Fixate
    The process whereby a CD’s overall lead-in, program data and lead-out areas are written. This is done during the track-at-once recording process when the final session is written, allowing all of the data contained on the disc to be read by any CD or CD-ROM drive.
  • Fixed formant
     A frequency characteristic of a sound, e.g. human vowel sounds, are formants which are relatively fixed in frequency, even though the pitch of the voice may be changing as in singing. It is the fixed formant frequencies in the presence of the varying pitch of a musical instrument that shapes the instrument’s timbre and makes the instrument recognizable.
  • Flamming
    An undesirable audio occurrence in which one of the instruments used on a rhythm track strikes slightly behind the others. It is caused primarily by the improper application of delay or tempo change.
  • Flange
    The round metal sides of a tape reel that keep the tape aligned as it winds onto the hub.
  • Flanging
    Named for the original effects technique where a second audio tape playback deck was slowed by a thumb on the reel flange, flanging is a special audio effect where a delayed version of a signal is mixed with the original signal, creating a swooshing sound. This is caused by the fact that when the time delay is different for the two combined signals, there will be frequencies where the phase-shift is 180? and the signals will cancel, causing deep dips or holes in the frequency response curve called the comb filter effect. As the speed is varied, the frequency of the dips is swept across the frequency range, giving the swooshing sound. Electronic flangers contain an adjustable electronic delay line. If the time delay is very short, the effect is called phasing. See also notch filter.
  • Flat
    (1) The condition of a note which is, either deliberately or accidentally, lowered in pitch. This might be only a few cents or as much as a tone (double flat, bb). In music notation, a flat is indicated by the flat symbol (b), meaning lower the tone by a half-step. (2) The same as dry. Unequalized, uncompressed, and otherwise unprocessed, describing a signal from any source: mic, instrument, or tape playback. (3) The neutral position on a tone control, effecting no change to the signal. See center detent. (4) Film projection using non-anamorphic lenses. In the U.S. the term flat is synonymous with an aspect ratio of 1.85:1 widescreen. See anamorphic.
  • Flat response
    The faithful reproduction of the amplitude of an audio signal, specifically, variations in output level of less than one decibel above or below a median level over the entire audio spectrum. A system which has the same gain at all frequencies of interest will yield a graph of the gain versus frequency that will be linear.
  • Flat wind
    To employ a slower-than-normal fast forward or rewind mode on a tape transport in order to wind the tape smoothly and evenly onto the reel or hub, usually for storage. Flat winding prevents edge curling and other types of deformation damage. See also heads-out.
  • Flattening
     A general term for the process of moving the final stems, tracks, etc. to audio/video tape, usually involving a substantial reduction in the number of tracks on which the sound is carried and merged with the time-coded video. Also specifically refers to the process in ProTools™ whereby stereo audio and video is exported to a QuickTime movie or other format.
  • Fletcher-Munson effect
     Fletcher and Munson measured the sensitivity of human hearing at various volumes and frequencies with the finding that humans hear best in the range of 3kHz-4kHz; the sensitivity falls off rapidly at lower frequencies and somewhat more slowly at higher frequencies. In other words, very soft sounds must be more powerful at frequencies lower and higher than 3kHz-4kHz in order to be heard. The loudness control on music reproduction systems was designed to compensate for the Fletcher-Munson effect. See equal loudness curves.
  • Flicker noise
    At high frequencies, intrinsic noise is dominated by Johnson noise. At lower frequencies, there exists a critical frequency, ƒ, at which noise rises proportional to 1/ƒ. Below this critical frequency, the noise is called flicker noise. Sometimes referred to as flicker effect.
  • Floating unbalanced output
    a phone-type output where the sleeve of the output stage is not connected inside the unit, and the ring is connected, usually through a small resister, to the audio signal ground. This allows the tip and ring to "appear" as equal impedance, not-quite-balanced output stage, even though the output circuitry is unbalanced. Floating unbalanced often works to drive either a balanced or unbalanced input, depending if a TS or TRS standard cable is plugged into the output. If a floating unbalanced connection hums, a ground-lift cable is required. Also known as a pseudo-balanced output, or quasi-balanced.
  • Floor
     In a noise gate, the amount of attenuation applied to an input signal whenever it is below the threshold level. For example, in a gate whose threshold is set to -10dBm and whose floor is set to -30dB, 30dB of attenuation is applied whenever the incoming signal drops below -10dBm.
  • Flutter
     (1) In a tape recorder, if the tape speed varies, the pitch of the recorded music will vary. If the rate of variation is fairly high, typically above 5Hz or so, it is called flutter. If the speed varies at rates below several HertzseveralHz, it is called wow. Flutter is actually a type of frequency modulation distortion and imparts a tremolo- or vibrato-like character to the music. (2) See chatter.
  • Flutter echo
     An acoustic effect where sound is reflected back and forth between two parallel surfaces such as walls. The same effect as standing waves, but at lower frequencies, flutter echo is created when reflections are lower than 15Hz, or when walls are greater than 25’ apart.
  • Flux
    Lines of force surrounding a magnet. In measuring the strength of a magnetic field at a particular location, the number of lines of force per unit area in a plane perpendicular to the direction of the lines. The standard reference unit in magnetic tape for recording is the nanoweber per meter, and is called flux density.
  • Fluxivity
     The numerical measure of maximum flux density a specific type of recording tape can hold. Reference fluxivity is a standardized amount of flux, specified in nanowebers per meter, which is laboratory-recorded on a test tape at various frequencies. Such reference tapes are used to calibrate tape recorder 0dBVU playback levels.
  • Fly in
     (1) To mix sounds from a non-sync source into the live sound for a TV show, or into the mix for a videotape production or spot. One may fly in a narrator, Foley, etc. (2) To record sections from one or more tracks of a multitrack tape onto a second recorder (generally a two-track), then copy them back onto the multitrack in another section of the performance. For example, one might take the background vocals from one chorus and fly them into another section of the song. Short fly-ins can be done without SMPTE sync, although it is somewhat difficult.
  • FM sync
    : The 13.5kHz frequency-modulated sync pulse recorded on Nagra IV-S recorders.
  • FM synthesis
    A sound synthesis technique which multiplies sine waves together in an attempt to generate complex waveforms more quickly (than additive synthesis), usually tends to add ing several of these products together in an attempt to get its more effective results, which is why a 6-operator FM sounds better than a 4-operator FM as more products are being summed. See sound synthesis.
  • Foldback
    The general term for the part of a sound reinforcement system in an auditorium which supplies amplified sound to the performers so they can hear themselves. See monitor mix.
  • Foldback send
    See monitor send.
  • Foldover
    See aliasing.
  • Foley
    Creating sound effects by watching the picture and mimicking the action, often with props. Foley artists, also known as Foley walkers, make use of a variety of objects and/or surfaces to elicit realistic sound effects; most commonly used in the recording of on-screen footsteps, hence the term "walkers." Foley effects are named after Hack Foley, who was the head of the sound effects department at Universal Studios. The audio track which contains Foley sounds is known either as a cloth track (west coast) or rustle (east coast.)
  • Foley
    Creating sound effects by watching the picture and mimicking the action, often with props. Foley artists, also known as Foley walkers, make use of a variety of objects and/or surfaces to elicit realistic sound effects; most commonly used in the recording of on-screen footsteps, hence the term "walkers." Foley effects are named after Hack Foley, who was the head of the sound effects department at Universal Studios. The audio track which contains Foley sounds is known either as a cloth track (west coast) or rustle (east coast.)
  • footage counts
     See counts.
  • Formant
     A frequency band in the spectrum of a voice or musical instrument that contains more energy or amplitude than the adjacent area, i.e., the partials are quite closely spaced in the region, giving the sound its timbre. For example, the formants produced by the human vocal tract are what give vowels their characteristic sound. See fixed formant.
  • Format
     (1) In vinyl records, the size of the disc and its rpm rating. (2) The physical specifications of a specific film or print, e.g., 35mm, as will as the type of soundtracksound track (optical or magnetic, stereo or mono, with or without NR), whether it is color or b/w. (3) The width of a videotape, and the designation of the electronic system by which it is recorded. (4) In radio and TV, the type of programming featured. (5) Magnetic tape format. For any tape recorder or recorded tape, the number of tracks, their width and position with respect to the tape, and the overall width of the tape itself. Tape speed is not always included, e.g., 8-track 1" and 24-track. This is usually called track format. (6) See file format.
  • Forward masking
     See temporal masking.
  • Four-stage envelope
     The Yamaha DX7 synthesizer introduced a new type of envelope generator, one which had four rate control and four level control parameters, for a total of eight parameters. Each rate parameter controls how long it takes the envelope to move from one level to the next. This is referred to as a four-stage envelope because each rate/level pair is considered a stage. Technically, an ADSR envelope only has one true stage, the decay/sustain stage and two more partially controllable stages because the attack and release levels were fixed at 100% and zero, respectively.
  • Four-track
    Sometimes called a quarter track refers to most home-type, reel-to-reel tape recorders which use one-fourth the width of the tape for each recorded track, allowing stereo signals to be recorded in both directions, doubling the recording time. Professional stereo tape recorders use one-half the tape for each track, resulting in better quality and reduced noise level. See magnetic tape. See also half track, two-track.
  • Fourier analysis
    A technique, usually performed using a DSP algorithm, that allows complex, dynamically changing audio waveforms to be described mathematically as sums of sine waves at various frequencies, amplitudes, and phases. The Fourier transform allows a function that represents an audio signal (signals are in the time domain because they exist in time) to be transformed to another function which represents the same signal in the frequency domain. The signal in the frequency domain is called a spectrum, and the same signal in the time domain is called a waveform.
  • Fourth
    The interval between a note and the one five half-steps above or below it. See interval.
  • Fox holes
    Small perforations on 35mm release prints that allowed for the addition of mag stripe for the CinemaScope process. This process has now largely been replaced by Dolby Stereo.
  • Fractal music
    Music created by the use of fractal equations. By assigning musical parameters such as pitch and volume to the x and y axes, it is possible to produce music as the Mandelbrot set is calculated.
  • Fractional
     Used by Telcos to describe a lower tier or service level of bandwidth. Fractional T-1 is a lower-bandwidth version of T-1 service offered at lower cost.
  • Frame
     The internal structural support of a loudspeaker when holds the voice coil and the diaphragm. (21) The basic unit of SMPTE timecodetime code, corresponding to one frame of a film or video image. Depending on the format used, SMPTE time can be defined with 24, 25 30 or 29.97 frames per second (fps). (32) In digital audio, a frame is a unit of digital information. In the CD, a frame covers six sampling periods, or 136µs.
  • Frame lock
    maintains synchronization between master and slave transports, using the positional information available in the timecode address. Also called frame sync. See SMPTE timecode.
  • Frame rate
    See frame.
  • Frame Relay
    An interface specification based on ISDN data link layer protocol.
  • Framing
     A self-contained unit of data, complete with addressing and control information.
  • Framing Bits
     Header and trailer structures that delimit the start and end of a frame of data.
  • Free-air
     Term relating to subwoofers which are designed to work most efficiently in free air using the boot for example, as an enclosure. Also known as “infinite baffle” The dilettante’s dictionary defines infinite baffle as “a loudspeaker which is constructed in a totally sealed enclosure so that it completely separates the sound radiated from its back. The opposite of a ported enclosure.
  • Free encoding
    An extension of spaced microphone recording techniques, systems which create pseudo-stereo from a mono source will also generate a strong surround signal, and stereo-width controls can be used to manage the balance between frontal and surround channels. Increasing stereo width also increases the level of the surround channel, whereas decreasing width reduces the surround content. This is because a surround decoder will automatically send anything which is of a similar level, but opposite polarity between left and right channels, straight to the surround output. Artificial reverberation, for example, is automatically spread across L, S, and R. See LCRS.
  • Free-field
     A sound source radiating into three-dimensional space where there are no reflecting surfaces is said to be radiating under free-field conditions. The SPL as measured at various distances from the source would obey the inverse square law precisely. There is no such thing as a true free-field, but it is approximated in an anechoic chamber. Because all rooms have at least a small amount of reverberation, the sound field from a source is always contaminated with reflected sound. See also far-field, near-field, reverberant field.
  • FreeMIDI
    A Macintosh operating system extension developed by MOTU that enables different programs to share MIDI data. For example, a sequencer could communicate with a librarian program to display synthesizer patch names, rather than just numbers, in the sequencer’s editing windows.
  • Freewheeling
    A condition in which a clock synchronizer continues to generate timecode even when it encounters dropouts in the timecode source, or in which a digital audio playback device continues to generate audio in the absence of, or while ignoring, a timecode input. See jam sync.
  • Frequency
    The number of waves (or cycles) arriving at or passing a point in one second, expressed in Hertz. See pitch, Appendix D.
  • Frequency band
    A frequency range or frequency band is a range of wave frequencies. It most often refers to either a range of frequencies in sound or a range of frequencies in electromagnetic radiation, which includes light and radio waves. Many radio devices operate within a specified frequency range which limits the frequencies on which it is allowed to transmit. The lower-bound and upper-bound frequencies are the points at which signal strength of the device falls off by 3dB.
  • Frequency distortion
     Frequency distortion results when the amplitude of the output of a system or a device varies as the frequency of the input varies, while the amplitude of the input is held constant.
  • Frequency doubling
     See doubling.
  • Frequency masking
    An audio artifact which occurs when several sounds are mixed, all which occur in the same frequency range. This happens because human ears tend to blend simultaneous sounds into a single, composite sound. When several instruments or other sounds emphasize similar frequencies, those frequencies accumulate and can either become too dominant or can cause one sound to mask another. Also called band masking or auditory masking.
  • Frequency modulation distortioN
     Examples of frequency modulation distortion are flutter and wow, and Doppler distortion caused by the motion of rotary (Leslie) loudspeaker cones.
  • Frequency modulation (FM)
    (1) A change in the frequency (pitch) of a signal. At low modulation rates, FM is perceived as vibrato or some type of trill. When the modulation wave is in the audio range, FM is perceived as a change in timbre. FM synthesizers, commonly found on soundcards, create sounds using audio-range frequency modulation. See FM synthesis. (2) Frequency modulation is the instantaneous changing of the frequency of a carrier in response to a modulation signal, usually an audio waveform. As the signal voltage varies up and down as it follows the waveform, the frequency of the carrier varies up and down from its nominal unmodulated value. The FM receiver is tuned to the carrier frequency, and the received signal, after suitable conditioning, is applied to a special circuit called an FM detector, also called a demodulator or discriminator, which recovers the audio signal. See amplitude modulation.
  • Frequency ratio
    The ratio of the higher pitch in an interval to the lower pitch. See consonant, harmonic.
  • Frequency response
     The amplitude response of a system or device as a function of the input frequency characteristic. It is a complex function which describes the way in which the gain and phase of a system or device vary with the frequency of the stimulus. Frequency response is a characteristic of a system or device, not a characteristic of a signal. See linear.
  • Frequency response curve
     A graph of the frequency response of a device, i.e., the graph of its output amplitude response vs. the input frequency. See linear. For example, tThe frequency response curve for a microphone is a graph of the mic’s output level in dBindB at various frequencies. The output level at 1kHz is placed on the 0dB line and the levels at other frequencies are placed above or below that reference level. The shape of the response curve suggests how the mic sounds; a wide, flat response tends to sound accurate and natural. A rising high end or a presence peak around 5-10kHz sounds more crisp and articulate. Note that the response curve is measured at a specified distance from the mic, usually 2-3 feet; the curve reflects the performance of the microphone only for that particular distance.
  • Frequency response errors
     Any deviation from a linear output response in an audio device.
  • Frequency shifter
    A device that linearly shifts all the frequencies of a complex input signal. Also called a spectrum shifter. All frequency components are shifted linearly, i.e., by the same number of Hertz, in contrast to a pitch-shift caused by changing the speed of a tape-reco. In such a pitch-shift, all the frequency components are shifted by a constant percentage, and therefore, high frequencies are shifted proportionally more than lower ones. A pitch-shift-by-speed change thus preserves all the musical intervals between components. A true frequency shifter, in contrast, destroys the harmonic relationships between the components. The sound of a consonant musical tone becomes disconsonant or clangorous or harsh, depending on the amount of shift. Frequency shifters are used in electronic music synthesizers for special effects.
  • Fringing
     A rise in the level of low frequencies when a recording is replayed by a tape head with a narrower track width than the one used to record the tape. Low frequencies from the recorded areas adjacent to those actually being played back bleed into the playback signal.
  • FSK
    Frequency Shift Keying. FSK is a sequence of two alternating audio tones, typically generated by a sequencer, drum machine, or computer MIDI interface, that is recorded on one track of an audio or video tape for synchronization to MIDI sequencers and drum machines. See pilot tone.
  • FTP
     File Transfer Protocol. A standard for sending and receiving files on the Internet. Provides basic insecure file and directory management between remote computer systems.
  • Full-coat
     Magnetic film coated with oxide across its entire width, available in 16mm and 35mm widths. Contrast with full stripe. See mag film.
  • Full code
     A term meaning that a sample word is set to all ones, i.e., that it is representing the largest number possible at that word length. This is important in the representation of digital audio amplitude, where a full code word is equivalent to -0dB headroom, or the amplitude that is the loudest sound which can be encoded without clipping. See also digital black.
  • Full Duplex
     An equal-bandwidth, bidirectional communications channel. Telephones are full duplex, while two-way radios (walkie-talkies) are (wireless) half-duplex. Bother Ethernet and PCI are half-duplex with one “talker” at a time.
  • Full Logic
     Feature of auto-reverse decks where fast-forward is always forwards, rewind is always rewind, regardless of tape play direction.
  • Full score
     A notated form of a piece of music which contains the complete music for all instruments or vocal parts, aligned vertically, i.e., t. The full complement of band parts.
  • Full-stripe
    Magnetic film with oxide coating in just the area where the recording takes place, allowing the transparent material to be written on. Contrast with full coat.
  • Full-track
    A 1/4" tape format in which a single, mono track is recorded across the entire tape width. Loosely used to refer to wider tape formats in which each of two or four tracks is 1/4" wide.
  • Fullth
    A subjective term applied to a recorded musical program with many voices in the lower mid-range of frequencies, e.g., cellos and violas, background vocals, rhythm piano, etc., giving the mix a lush or heavy richness. Also called gush.
  • Fundamental
     The perceived pitch of a sound; the lowest frequency pitched vibration component in a complex sound which also carries a set of higher-pitched vibration called overtones. The fundamental is always the first harmonic and/or partial component of a sound. See DCO.
  • Fusion
    In stereophonic music reproduction, fusion is the perception that sounds from two or more loudspeakers are being produced by a single sonic image.
  • Fuzz box
     An effects device designed to produce clipping distortion, most frequently used with electric guitars. See DI.
  • Fx
     See effects.
  • G722
    An international telecommunications standard for data reduction used for limited-bandwidth speech over digital telephone networks; used only in basic ISDN applications.
  • Gaffer
    (1) On a film set, the head electrician, now more commonly called the "Chief Lighting Technician." (2) In film, the head of a crew, e.g., the "gaffing mixer" would be the re-recording mixer-in-charge, formerly known as the gunner.
  • Gain
     The output voltage of a device divided by its input voltage. Most passive devices have a negative voltage gain, and most active devices, especially amplifiers, have a positive voltage gain. Usually expressed in dBindB, this is correct only if the input and output impedances are the same, a condition not usually met. The square of a voltage ratio is a power ratio if the condition of matched impedances is met. See amplifier gain, impedance-matching.
  • Gain-before-threshold
     In a compressor or limiter, the decibel gain applied to signals below the threshold level, i.e., before the compression circuit.
  • Gain control
     The fader that controls the strength of the output signal of an amplifier. This term is misused on many amplifiers, since the gain remains constant, while the gain control actually adjusts the signal input level. Also erroneously called volume control on consumer equipment.
  • Gain riding
     Manual, real-time volume control during recording to prevent overload and distortion at loud levels, and to avoid noise problems at low levels.
  • Gain stages
     Electronic components (or sets of components) whose purpose is to provide signal amplification in an active device.
  • Gallows arm
     A type of mic stand which consists of a vertical section, to the top of which is fitted an adjustable rod which carries the microphone.
  • Galvanic isolation
     In transformer, galvanic isolation means that no electrical current can flow directly from one winding to the other as they have no direct electrical contact. However, a signal can flow between the windings via electromagnetic coupling.