A modulation view of audio processing for reducing audible artifacts

When manipulating audio signals, frequency decomposition, gain functions, and temporal behavior can be understood in terms of modulation effects and their perceptual impact. For example, audio enhancement or dynamic range control both rely on spectral gain functions that fluctuate rapidly enough to adapt to changing signal characteristics. However, rapid fluctuations in gain effectively modulate the signal, resulting in perceptual artifacts. This paper discusses the perceptual impact of modulating gain and trade-off between temporal responsiveness and perceptibility. We demonstrate that, in many situations, it is best to apply gains in subbands that are similar to critical bands in the human auditory system and that the gain function in each subband should be low-pass filtered with a cutoff frequency proportional to the subband bandwidth.