Muting Sounds
You can mute a sound so that it is inaudible.  The reason you might do this is to keep a sound in the project without having to listen to it.  A muted sound will appear light gray.  If you mute a track, it will mute all sounds on that track.  To mute a sound, select it and then choose Mute from the Sound menu.  Alternatively, you can go to the Sound Details Tab and click on the mute button (looks like a speaker).