title: Automatic Gain Control(AGC) for external mic
body: <p>I have an audio recording app on android market which records using PCM-WAV format.
  My app also offers <code>custom gain control ([-20dB, +20dB])</code>, so I alter the original audio data with user selected gain value.</p>
  
  <p>It works pretty well when using device built-in mic, but I have a user which uses some <code>external mic plugged into his device, and the output is too loud and full of distortions</code> (because of the loudness of his ext mic). Even when he set the gain to -20dB, the output is loud and contains distortions.</p>
  
  <p>I thought I should add AGC control into the app for cases as this. </p>
  
  <p>Now my question: 
  This AGC only applies when using <code>DEVICE BUILT-IN mic? Or it applies also when using an ext mic plugged into the handheld?</code></p>