I have a 2008 mac pro bought in October. Today for the first time I'm hearing occasional strange sounds coming from my Mac Pro. Kind of like a quick spitting sound that lasts about half a second. I may hear it a few times within a couple of minutes, then I may not hear anything again for quite awhile. They get louder when I turn up the volume so I assume it's from the speaker. Maybe a short or something? The last thing I did yesterday was try out all the voices for announcing the time. Any ideas? Am I going to have to call apple? I'm not very technical except for simple stuff like adding memory and drives.