i had this problem after udating to ios6 on my ipad and after updating to ios 7.
i fixed this problem this way twice
get into your ipad root directory and go to
/System/Library/LaunchDeamons and locate the file com.apple.iapd.plist
Had the same jarring audio problem with ipad mini. It did not work restoring the general settings, but it did work when I restored Network settings. Weird.
I also have the exact same problem. However, I always get it fixed by rebooting the iPad. Just click the home button and the Shut down button together at the same time for a long time until an Apple logo appears. After rebooting, the ipad should have normal sound. I always get it fixed like that, so hope it works for you too!