No Audio at All

I get no audio whatsoever when running the game. No menu sounds, environment/mob sounds, music (ambient or with records).

In-game volume settings set to max, I am able to get all other audio from my PC but for some reason Minecraft isn't outputting anything audible. Maybe a loop of silence being played, I don't know how to check for that but it's a possible cause.

Reverting to 1.7.10 or earlier, including any other snapshots, audio returns and functions normally.