[GAMEPLAY] High pitched everything

I play on a MacBook Pro, with an especially old OS (OS X 10.8.5 to be exact) and I constantly get bugs. I just played a game and all the sounds in game were really high pitched. Sound effects, ambience, attacks, deaths and everything else. I reset all the sounds, muted then unmuted, I did basically everything except disconnect or close the client. I think it's just the league client update or my computer, but I was wondering if anyone else has had the same problem. It could be a one time thing though but I don't know.