class RecordThread extends Thread{ 
  static final int frequency = 44100; 
  static final int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO; 
  static final int audioEncoding = AudioFormat.ENCODING_PCM_16BIT; 
@Override 
public void run() { 
  // TODO Auto-generated method stub 
  int recBufSize = AudioRecord.getMinBufferSize(frequency, channelConfiguration, audioEncoding)*2; 
  int plyBufSize = AudioTrack.getMinBufferSize(frequency, channelConfiguration, audioEncoding)*2; 
  AudioRecord audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency, channelConfiguration, audioEncoding, recBufSize); 
  AudioTrack audioTrack = new AudioTrack(AudioManager.STREAM_MUSIC, frequency, channelConfiguration, audioEncoding, plyBufSize, AudioTrack.MODE_STREAM); 
  byte[] recBuf = new byte[recBufSize]; 
  audioRecord.startRecording(); 
  audioTrack.play(); 
  while(true){ 
    int readLen = audioRecord.read(recBuf, 0, recBufSize); 
    audioTrack.write(recBuf, 0, readLen); 
  } 
  audioTrack.stop(); 
  audioRecord.stop(); 
  } 
}