You know, I am a musician, have several hundred tracks of my music (just acoustic folkie stuff, fingerpicking tunes, etc.) mostly on soundcloud and there is a term in audio recording called 'Ducking' also.
It refers to an automatic lowering of an instrumental track when electronically compared to a reference track which would happen to be a vocal say.
So when the vocal track gets louder, the instrument track gets to gain some DB of volume, but when the vocal volume goes down the instrument track goes down with it, the idea being vocals don't want to be drowned out by loud instruments because folks want to hear the vocals a bit more than they want to hear the instruments.
So it is called audio ducking.