Elaine Sy

A noise gate is a handy effect that is pretty easy to put into practice, since most audio software seems to come bundled with it these days. The idea is basically to let all audio be heard ONLY if it is loud enough – so, the stuff you WANT to be heard, like the music, the voice, etc. When the volume drops below a certain level (when it gets quiet enough), everything gets turned down to SILENT. The idea is that background noise will be eliminated when the signal – the thing you WANT to be heard – stops. It’s original idea was to improve audio quality by mopping up noise in between the signals. But you can also use this effect to make drums and other percussive music elements do some cool stuff.
More information found in this article http://en.audiofanzine.com/getting-started/editorial/articles/enhancing-percussive-elements-with-a-noise-gate.html