I recently installed Ubuntu 14.04 from scratch, overwriting 13.10. Ever since then, I haven't been able to play audio in most desktop media applications: Spotify, Rhythmbox, Pithos, Banshee...all of them show that they're playing a song (including a libnotify popup), but no sound comes out, and the application's progress bar doesn't move. Web applications (flash, HTML5 in Firefox/Chrome) can still play audio just fine, and desktop applications that do not use indicator-sound (e.g., Audacity) can, too. The one indicator-sound application that I've found that can play audio is VLC.
Any suggestions for how to fix this?
EDIT: Just to be perfectly clear, I do have audio in most applications (VLC, Firefox, Totem, Audacity, etc.). It's specific music applications that are affected. I think it might have something to do with gstreamer (although that wouldn't explain why Totem works).