title: Mic and Speaker Feedback
body: <p>I have an iPad application (a tuner) that uses Core Audio Audio Units. It reads the signal from the mic and processes it. It does NOT echo the sound to the speaker.</p>
  
  <p>Unfortunately, at different times, the signal actually feedbacks and comes out of the speaker - loud and sort of phasey. I haven't made any connection from the mic to the speaker - but it creates the illusion that the mic is somehow "on". It isn't a direct signal - it is chopped up and requires you to make somewhat loud noises before it will happen.</p>
  
  <p>I'm concerned this is related to overloading the cpu or something. I don't think the callback is getting behind. If I put debug statements into the callback, they seem to stop when I turn off the Audio Unit ... which brings up another oddity. At certain times, even when the Audio Unit has been stopped, the feedback continues to occur from the mic to the speaker so that the app has to be shutdown and removed from the background processing queue before the incessant noise stops.</p>
  
  <p>Oddly, this doesn't happen every time and to every tester but it does occur often enough to create a stir.</p>