Mute Notification Center Alert Sounds in OS X Mountain Lion

Notification Center is a great addition to OS X Mountain Lion but the alert sounds can be pretty annoying if you have a lot going on. Rather than muting all system audio to hush the constant chiming, you can directly silence notifications on a per-app basis.
- Open System Preferences from Apple menu and click the “Notifications” menu
- Select apps from the left and uncheck the “Play sound when receiving notifications” box
- Repeat for every app you want to silence
This better than disabling Notifications completely because you’ll still see them arrive, but you won’t bother your coworkers with beeps and boops anytime it’s your turn in Chess.
If anyone knows of a way to turn off alert audio for all notifications in OS X, let us know in the comments!

Option+Click the icon and it disables notifications temporarily, do that when you want quiet. Do it again when you want alerts. Much easier than playing with settings amirite?
When the Notification column is open scroll to the top and there is an ON and OFF button too.
This is annoying me – I’ve turned off sounds for mail notifications in both Mail and Notifications and I still get a bloody deep beep every time I get an email!
I can’t turn it off. Only happens on my new MacBook Air, not my iMac.
Anyone got a suggestion?