My 13'' mid-2013 MBA is having strange sound problems. When I listen to iTunes, the music and any other sounds periodically stop. After about 30 seconds, they start back. During the silent times, there is nothing I can do to change the volume. The music pauses itself and won't start back until the sound comes back. When I go to sounds it says it's using my headphones as output, but no sounds come out. If I unplug them, it says Internal Speakers as output, but still no sound comes out. Plugging and unplugging doesn't fix it. I tried restarting and that worked for a while but now it's back. What's going on?!