- The process of restoring an audio frequency signal to its original form before reproduction. This is done to offset the preemphasis of higher frequencies occurring prior to transmission or during recording. May be used, for instance, in frequency-modulated receivers. The utilization of preemphasis followed by postemphasis may help improve the overall signal-to-noise ratio and reduce distortion, among other benefits. Also spelled postemphasis. Also called post-equalization, or deemphasis.