I've just started getting a weird sound issue. Basically, Vocals (and anything around that frequency) either play super quietly or won't play at all. I get this issue in itunes, youtube, spotify, anything- No matter where I go, my computer refuses to play sounds around the 'vocals' range of frequencies. It's just silence, whilst all other frequencies (guitar, drums, explosions etc) play fine. 
 
What seems even weirder to me is that if I balance the sound to my left or right speaker, either using the windows sound manager thing or one that game with software for my soundcard, the vocals suddenly burst back onto the scene. Obviously I can't just leave it balanced to just one speaker though, as I use headphones and it just sounds plain wrong, not to mention i'd miss anything playing through the other track. 
 
Does anyone have any idea what's going on?