title: android as a ultrasonic sound emitter and receiver
body: <p>I want one of my android phones to emit sounds that are unhearable by human, and the other to listen to it and analyse frequency and so on.
  Is it even possible?</p>
  
  <p>And my next question is - can mic support two channels? I want to analyse if the sound comes from the left of my device or right of it. Is it possible?</p>