What is Sidechain Compression?

Sidechain compression is a technique in audio production where a compressor on one sound is controlled by the signal of another sound. Instead of responding to the volume of the track it is placed on, the compressor reacts to a separate input called the sidechain. This allows one sound to automatically reduce the volume of another when it plays.

A common example of sidechain compression occurs in electronic and dance music, where a kick drum triggers compression on a bass line or synthesizer. Each time the kick drum hits, the compressor briefly lowers the volume of the other sound, creating a rhythmic “pumping” effect. This technique helps the kick drum stand out clearly in the mix while preventing low-frequency elements from clashing.

Sidechain compression is also widely used in mixing for practical purposes such as improving clarity between competing sounds. For example, a voiceover track can trigger compression on background music so the music automatically lowers when someone speaks. This makes sidechain compression both a creative sound design tool and a useful mixing technique.