Program-dependent release means that rather than being set to a fixed value, the release time of a compressor varies somewhat depending on the frequency and amplitude of the incoming signal. This allows the compressor to respond to what is happening in the program (audio) material that is passing through it, and can reduce artifacts such as pumping and harmonic distortion from attack-release cycles. Compressors featuring program-dependent release include the Universal Audio LA-2A, Manley Labs EL-OP, and Fairchild 670.
