Sidechain Compression

Sidechain compression, aka ducking, is an audio effect typical in radio, pop, and dance music. In this compression, the presence of an audio signal decreases the level of another audio signal. Radio achieves this effect by lowering the volume of the second audio track when the first one begins to increase the volume or when it completes the overall process.

Some Examples of Sidechain Compression

As mentioned before, daily radio production routine employs sidechain compression with frequency. This effect is able to create a voice-over. A professional speaker reading a translation dubbs and ducks the foreign language of the original sound. When the translation begins, the ducking becomes active. In regards to music, producers usually apply the ducking effect in situations where the volume of one signal lowers by the presence of another signal. In essence, the ducked track is quieter when the ducking track gets louder.

How It Works

People associate this compression to a very specific use. When the user feeds a regular 4/4 kick drum into the sidechain input of a compressor with a high-ratio, a low-threshold, a fast-attack, and a medium-to-low release, the sound is prone to duck when the kick drum appears. This effect occurrs because the kick drum causes the compressor to reduce its levels every time a sound appears. When you combine the effect, any compressed sound mimics a pumping or sucking noise. It’s worth mentioning that, by applying sidechain compression to the whole track, the resulting effect might be pretty extreme.


The sidechain compression effect might give the impression that the track is louder than it actually is. Both the human ear and a listening or recording device has limits regarding the loudness of sounds. Eventually, the sound might get distorted or overloaded, and the human ears tend to compress sounds that get louder. If the producer sets the sidechain compression in the right direction, it might have the same effect as the one achieved when listening to extremely loud noise. 

It’s natural for the human ears to mark a difference between the extremely loud effect and the sidechain compression effect. This situation is unique because it gives the impression that the listener is hearing something in a very loud and a very quiet volume simultaneously. A bigger mix is a useful side-effect of the sidechain compression process.