If you've spent any time hanging out in Dalaran recently you've no doubt seen your fair share of flying star unicorns and probably have heard non-stop the lamentations of Lil' XT.
There was previously a bug that caused Lil' XT's sounds to be sent out to a much wider range than they were supposed to be heard. When a few dozen people have them out it can get quite annoying. There's now a hotfix that disables some of these sounds. It's not a complete solution, but it's better than turning off sounds all together.
Vaneras is an EU community manager, and we're not sure if the hotfix is active in the US. However, if it's not in the US right now I'm sure it will be soon.