aux or 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.
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 /: See AVC.
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.
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.
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.
A-type : See Dolby noise reduction.
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 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 : See AF.
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.