For its fancy sounding name and esoteric roots, sidechain compression is an extremely simple studio technique both in principle and practice. What is sidechain compression? Basically, it is the same as ordinary audio compression except that it uses another audio source as its input, and then uses the resulting gain reduction on the destination audio track. The most common application of this method is in the ubiquitous ‘ducking’ or ‘pumping’ effect heard peppered throughout just about every dance track recorded in the last 15 years. This effect is achieved by using the kick drum as the sidechain input, which then sends the resulting gain reduction to, usually, a sustained sound on another track like a pad, chord, or noise loop.