I was born with bad hearings, so when I was younger I had to do these tests, where they put head phones on my head, then when I heard a beep (very annoying beep, one that pierces right through your cranium) I had to press a button (there where 2 buttons, on for left and one for right, so when I heard the beep in the left of the head phones I had to press the left button via versa on the right), sometimes I can still hear that annoying beep when it's quiet, I never had it with AIM/MSN notices though, I simply turn them off and don't think about it