I tweaked and clarified a bit more to my personality and background, so I hope that helps. With Sound Manipulation, I was thinking of it more as a personal thing. He can mostly just control the sound he makes, and the bubbles are only small. He could use it to project or quiet down his own sounds (his instruments/voice) and shut out sound so he doesn't have to listen to anyone.

Zac: *nods at Ev, grinning* Yes, let's do it!