Echo sound when record and play from bluetooth headset

I have been finished a project about record and play the sound from Bluetooth headset. It works now. We can speak into headset device and it will record and play directly in speaker of android phone. However, I have a problem that need your help. During the playing, my audio file has echo sound. I am not sure what is happen in my application. But I think the sound may be from MIC in android phone. Please try to look at my project and let me know how to fix it. Thank you in advance This is my sound and my project file download This is my setting

private void initRecorder() {
    int bufferSize = AudioRecord.getMinBufferSize(SAMPLE_RATE, AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT);
    mBuffer = new short[bufferSize];
    mRecorder = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION, SAMPLE_RATE, AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT, bufferSize);

And record and play file

private void startBufferedWrite(final File file) {



        new Thread(new Runnable() {
            @Override
            public void run() {
                DataOutputStream output = null;
                try {
                    output = new DataOutputStream(new BufferedOutputStream(new FileOutputStream(file)));

                    short[] lin = new short[1024];
                    int num = 0;
                    ///////////Play during recording
                    track.play();

                    while (mIsRecording) {
                        double sum = 0;
                        int readSize = mRecorder.read(mBuffer, 0, mBuffer.length);
                        //num = mRecorder.read(lin, 0, 1024);
                        //track.write(lin, 0, num);
                        track.write(mBuffer, 0, readSize);
                        for (int i = 0; i < readSize; i++) {
                            output.writeShort(mBuffer[i]);
                            sum += mBuffer[i] * mBuffer[i];

                        }
                        if (readSize > 0) {
                            final double amplitude = sum / readSize;
                            //AppLog.logString(String.valueOf(((int) Math.sqrt(amplitude))));

                            double dbAmp=20.0 *Math.log10(amplitude/32767.0);
                            AppLog.logString(String.valueOf(dbAmp));


                        }
                    }
                } catch (IOException e) {
                    Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT).show();
                } finally {

                    if (output != null) {
                        try {
                            output.flush();
                        } catch (IOException e) {
                            Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT)
                                    .show();
                        } finally {
                            try {
                                output.close();
                            } catch (IOException e) {
                                Toast.makeText(MainActivity.this, e.getMessage(), Toast.LENGTH_SHORT)
                                        .show();
                            }
                        }
                    }
                }
            }
        }).start();
    }

    _audioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE);
    int maxJitter = AudioTrack.getMinBufferSize(SAMPLE_RATE, AudioFormat.CHANNEL_OUT_MONO, AudioFormat.ENCODING_PCM_16BIT);
    track = new AudioTrack(AudioManager.MODE_IN_COMMUNICATION, SAMPLE_RATE, AudioFormat.CHANNEL_OUT_MONO,
            AudioFormat.ENCODING_PCM_16BIT, maxJitter, AudioTrack.MODE_STREAM);
    _audioManager.startBluetoothSco();
    _audioManager.setMode(AudioManager.STREAM_SYSTEM);  
    _audioManager.setSpeakerphoneOn(true);
    //_audioManager.setMicrophoneMute(true);
    setVolumeControlStream(AudioManager.MODE_IN_COMMUNICATION);
    }