every so often my macbook pro will emit a very strange noise coming from the speakers. it goes with the volume bar so i know it is coming from the speakers and not from the mechanical parts. the stranger part of this problem is that if i plug in external speakers, it is emitted from those speakers. i don't have anything weird running; the only 3rd party apps on right now are adium, utorrent, and firefox. I also cannot re-create it it just happens every now and then. a restart usually fixes it too. what could be the cause of this? here is a youtube video of the noise, it actually has more bass than it sounds like. http://www.youtube.com/watch?v=J1cefTrm6pA BTW this is NOT the same thing as the speaker rattle in the other thread. this is when no programs are making any noise.