Sudden sounds in Mountain Lion I run Mountain Lion on my macbook pro, and experience an unusual effect: sometimes system sounds happen, without any visible reason.
Does anybody know, why it could be?
Or, if it is possible, how to monitor the audiu subsystem to find out what application and when plays sounds.
There are a couple of things you can do figure out what's going on. First, see if it happens within other users. When it happens, see what Applications you're running, through Terminal or Activity Monitor, and check the Console, which logs all system's messages, and see if any of the running Application is sending any warning or having any issue.

All of these Apps can be found under Applications / Utilities.