Occasionally, when I've had my mac on mute for a period of time (eg., several hours), and then plug in a set of headphones, I get a backlog of system sounds played to me. (chirps, new email sounds, etc).
These are sounds that would've/should've been played over the day, but weren't. It seems the sounds are queued / buffered, then when I plug in my headphones, the queue is emptied.
What causes this, and how do I prevent this?