Facebook notification sound in OSX: cannot switch off

In OSX Mountain Lion I'm getting beeps every time a facebook notification comes in. In System Preferences > Notifications > Facebook i have set my alert style to None. In the list on the left, the text below "Facebook" shows "Badges, Sounds". It gives me no method of turning off Badges or Sounds.

Mail, Skype and others have two additional checkboxes visible: "Badge App Icon" and "Play sound when receiving notifications". Neither of these are visible on the Facebook item.

So it appears impossible to turn off the sounds?

I found it. Account Settings>Notifications>How You Get Notifications>On Facebook>Play a sound when each new notification is received (UNCHECK the box). So far, it seems to be working. Whew. Thanks, Steve.