Audio ducking is a process whereby sound is “ducked” down when another sound goes beyond a particular threshold. The volume of the audio track which is the background track is temporarily lowered to allow the main track to take prominence.

This is sometimes done by using compression, though it can also be done by a simple volume adjustment. Whichever method is used, though, the result is the same, which is that one track is made more distinct and clear than the other.

Applying either a reduction in volume or compression can be done automatically or manually but most digital audio workstations (DAWs) will allow you to do it automatically and it greatly simplifies the process.