AudioTrack cannot play audio to speaker in mobile

I am new member of Android and I have a problem that need your help. I am making a project that can play the sound that coming from headset Bluetooth. I am using SCO to receive and AudioTrack to play during receiving. The receiving task is done. But the playtask help some problem is that I cannot hear the sound in the speaker of mobile (only hear in earphone of headset device), although I set

_audioManager.setSpeakerphoneOn(true);

For playing task I used this code

_audioManager.startBluetoothSco();
_audioManager.setMode(AudioManager.STREAM_MUSIC); 
_audioManager.setSpeakerphoneOn(true);
recorder = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION,
            RECORDER_SAMPLERATE, RECORDER_CHANNELS,
            RECORDER_AUDIO_ENCODING, BufferElements2Rec * BytesPerElement);
 int maxJitter = AudioTrack.getMinBufferSize(8000, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);
  track = new AudioTrack(AudioManager.MODE_IN_COMMUNICATION, 8000, AudioFormat.CHANNEL_OUT_MONO,
            AudioFormat.ENCODING_PCM_16BIT, maxJitter, AudioTrack.MODE_STREAM);

  track.play();
  recorder.read(sData, 0, BufferElements2Rec);
  try {
                // // writes the data to file from buffer                           
                byte bData[] = short2byte(sData);
                track.write(bData, 0, BufferElements2Rec * BytesPerElement);
                } catch (IOException e) {
                e.printStackTrace();
       }

This is my full code. Please run it and let me know the problem link