Inside voices, anyone?

You know what's really annoying?  People in the library who have no idea what an inside voice is.  Granted, I'm in one of the areas that has space for group study, but the vast majority of people here are polite enough to try to keep their voices down.  These guys have been talking as loud as they feel like for at least a couple of hours.  I can hear them over my music and sound-proof headphones.  They seem to finally be getting ready to leave, but it's really really irritating.  Grr.