Audiotent Tip 355. Vocal Noise Gate.
A noise gate is a very effective tool for removing unwanted background noise during quiet sections of a recording.
This is especially useful on vocals and is a lot faster than automating or recording manual volume fades.
One of our favourite plugins for this task is the UAD 235L Gate/Expander from the API Vision Channel Strip.
Simply apply the plugin to your vocal track or group, flick the 235L into gate mode, set your attack to normal and dial in the threshold to taste.
The final result is a tight vocal track, free of any unwanted background noise.