Currently Being ModeratedOct 27, 2011 4:04 PM (in response to Azurite)
MIght not be an Apple app. Look through your third party programs>preferences for possible culprits.
Currently Being ModeratedOct 27, 2011 4:10 PM (in response to WZZZ)
It turns out it's happening every 20 minutes, on the "8"-- 3:38, 3:58, 4:08. The sound isn't actually "glass" but similar to it--like a very light "ding."
I've tried checking the preferences for what I have open, but either there's no preference for notifications/alerts, or there's nothing regarding sounds.S
Currently Being ModeratedOct 27, 2011 5:28 PM (in response to Azurite)
It turns out it's happening every 20 minutes, on the "8"-- 3:38, 3:58, 4:08.
Sounds like you have some kind of alarm clock app installed. Have you installed any? If so check your login items.
Currently Being ModeratedOct 27, 2011 7:11 PM (in response to X423424X)
I have BusyCal installed, but no alarms that I could find.
However, I do think I've found the source of the sound: the Firefox add-on "LiveJournal." It routinely checks my LJ and plays a "ding.wav" file whenever there are new posts to my Friends' page. I noticed that the sound started happening more frequently, but after I closed Firefox, it stopped. But since Firefox didn't have any sound/notification settings on its own, I thought to check the extensions, and voila!
I'm pretty sure the problem is solved, but who knows if the sound will mysteriously return...I
Currently Being ModeratedOct 27, 2011 7:47 PM (in response to Azurite)
At first, based on your description, I thought it might be Mail.app alerting you that a new message has arrived. In Mail's "Preferences>General" you have the option to make the "New Message" alert sound "Ping" or "Glass" among others. However, the frequency options are manually or every 1, 5, 15 or 30 minutes, but no option for every 20 minutes.
If you don't use Mail.app and if it turns out not to be Firefox, check your email app.