Ducking audio has been used for many decades, most often to make space for the voice over by ducking the background music.
What is Ducking in Audio and Music?
Ducking basically means to heavily reduce the level of one audio signal, when the more important audio is present. It’s basically the same thing as sidechain compression, but it can do more than that.
While sidechain compression in modern music production is mainly used to duck 1 instrument track, while another is playing (for example ducking the bass every time the kick hits)…ducking can be used to reduce the level of “wet effects” like delay and reverb, when the dry signal is present.
This means that you can avoid that muddiness and cloudiness that a big reverb or lots of delay can do on a vocal or any important lead instrument.
Because on every syllable and word when vocal is present, the reverb and/or delay is ducked, and then in between the words and phrases ducking stops and it opens up that huge space you created.