SVA : Stereo Variable Area. A motion picture sound system consisting of two closely spaced optical variable-area soundtracksound tracks on 35mm film. Dolby improved this format with their Dolby-Acompander system to improve the SNR, as well as employing Scheibermatrixing to synthesize a third (center) and fourth (surround) channel for surround-sound applications. Most modern movies with stereo soundtracksound tracks employ the Dolby SVA system. See snake track.