This is an application which will keep all your microphones muted until you press a designated key (push to talk).  It also reduces the volume by an adjustable level of all the other applications while the key is down.  It works globally, so it will still work running in the background while a full screen application, such as a game, is in the foreground.  It's intended to add Push To Talk and Volume Reduction functionality to voice applications that don't have it.