Ducking

Ducking is an effect commonly used in radio and pop music, especially dance music. It is an effect where the level of one signal is reduced by the presence of another signal, through the use of side chain compression.

A typical application is to automatically lower the level of a musical background track when a voice-over starts, and to automatically bring the level up again when the voice-over stops (in Movies and on radio-broadcasts).

Ducking has long been a popular technique particularly in techno or dance music to tighten up the low end and increase the impact of the kick drum, or even to create pumping effects. When mixing your kick and bass sounds together you may find that some frequencies are overlapping and conflicting with each other causing a muddy low end. A great way to solve this problem and build a solid low end is to “duck” the bass in response to the kick drum with side chain compression. Essentially what this does is decrease the volume or amplitude of the bass on every kick drum hit.