problem
Sidechain ducking creates space by letting one sound momentarily move another out of the way.
Sidechain ducking uses one signal to trigger gain reduction on another. A common example is a kick drum lowering a bass or pad for a short moment.
The goal is not always an obvious pumping effect. Often it is just enough movement to make the trigger sound clearer.
Fast attack makes the duck happen immediately. Release controls how quickly the reduced sound returns. If release is too fast, the movement chatters; too slow, the mix loses energy.
The threshold and ratio decide how much the target moves when the sidechain signal arrives.
Filter the sidechain or use frequency-specific ducking when only part of the sound masks the trigger. Full-band ducking is simple, but it can make the whole mix breathe.
Match the bypassed and processed loudness so the ducking decision is based on clarity, not extra level.