android AcousticEchoCanceler doesn't seem to work on most devices
<p>I am building an application which requires the mic to cancel any sound coming from the speaker. It seems that this issue is almost a conspiracy on-line as others with the exact same problem were never responded to for an extended duration. </p>

<p>Android's native hardware accelerated AcousticEchoCanceler does not seem to work on most devices. Tests where made on many devices and the ones that seemed to work Include Nexus 5, and Moto X while almost all Samsung devices tested could not remove background sound.Note: All phones tested return true for <code>AcousticEchoCanceler.isAvailable()</code></p>

<p>However, there must be a solution since applications such as Skype or WhatsApp seem to cancel sounds outside their app context, i.e. a call is on speaker and the Microphone cancels any feedback received.</p>

<p>This simplified recording app records sound to a file and plays it later when play is clicked. </p>

<p>MainActivity.java</p>

<pre><code>public class MainActivity extends Activity {

Button startRec, stopRec, playBack;
int minBufferSizeIn;
AudioRecord audioRecord;
short[] audioData;
Boolean recording;
int sampleRateInHz = 48000;
private String TAG = "TAG";

/**
 * Called when the activity is first created.
 */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    startRec = (Button) findViewById(R.id.startrec);
    stopRec = (Button) findViewById(R.id.stoprec);
    playBack = (Button) findViewById(R.id.playback);

    startRec.setOnClickListener(startRecOnClickListener);
    stopRec.setOnClickListener(stopRecOnClickListener);
    playBack.setOnClickListener(playBackOnClickListener);
    playBack.setEnabled(false);
    startRec.setEnabled(true);
    stopRec.setEnabled(false);

    minBufferSizeIn = AudioRecord.getMinBufferSize(sampleRateInHz,
            AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT);

    audioData = new short[minBufferSizeIn];

    audioRecord = new AudioRecord(MediaRecorder.AudioSource.VOICE_COMMUNICATION,
            sampleRateInHz,
            AudioFormat.CHANNEL_IN_MONO,
            AudioFormat.ENCODING_PCM_16BIT,
            minBufferSizeIn);

}

OnClickListener startRecOnClickListener
        = new OnClickListener() {

    @Override
    public void onClick(View arg0) {
        playBack.setEnabled(false);
        startRec.setEnabled(false);
        stopRec.setEnabled(true);
        Thread recordThread = new Thread(new Runnable() {

            @Override
            public void run() {
                recording = true;
                startRecord();
            }

        });

        recordThread.start();

    }
};


OnClickListener stopRecOnClickListener
        = new OnClickListener() {

    @Override
    public void onClick(View arg0) {
        playBack.setEnabled(true);
        startRec.setEnabled(false);
        stopRec.setEnabled(false);
        recording = false;
    }
};



OnClickListener playBackOnClickListener
        = new OnClickListener() {

    @Override
    public void onClick(View v) {
        playBack.setEnabled(false);
        startRec.setEnabled(true);
        stopRec.setEnabled(false);
        playRecord();
    }

};


@TargetApi(Build.VERSION_CODES.JELLY_BEAN)
private void startRecord() {
    File file = new File(Environment.getExternalStorageDirectory(), "test.pcm");

    try {
        FileOutputStream outputStream = new FileOutputStream(file);
        BufferedOutputStream bufferedOutputStream = new BufferedOutputStream(outputStream);
        DataOutputStream dataOutputStream = new DataOutputStream(bufferedOutputStream);

        NoiseSuppressor ns;
        AcousticEchoCanceler aec;

        if (NoiseSuppressor.isAvailable()) {
            ns = NoiseSuppressor.create(audioRecord.getAudioSessionId());
            if (ns != null) {
                ns.setEnabled(true);
            } else {
                Log.e(TAG, "AudioInput: NoiseSuppressor is null and not enabled");
            }
        }

        if (AcousticEchoCanceler.isAvailable()) {
            aec = AcousticEchoCanceler.create(audioRecord.getAudioSessionId());
            if (aec != null) {
                aec.setEnabled(true);
            } else {
                Log.e(TAG, "AudioInput: AcousticEchoCanceler is null and not enabled");
            }
        }
        audioRecord.startRecording();

        while (recording) {
            int numberOfShort = audioRecord.read(audioData, 0, minBufferSizeIn);
            for (int i = 0; i &lt; numberOfShort; i++) {
                dataOutputStream.writeShort(audioData[i]);
            }
        }

        audioRecord.stop();
        dataOutputStream.close();

    } catch (IOException e) {
        e.printStackTrace();
    }
}

void playRecord() {
    File file = new File(Environment.getExternalStorageDirectory(), "test.pcm");

    int shortSizeInBytes = Short.SIZE / Byte.SIZE;

    int bufferSizeInBytes = (int) (file.length() / shortSizeInBytes);
    short[] audioData = new short[bufferSizeInBytes];

    try {
        FileInputStream inputStream = new FileInputStream(file);
        BufferedInputStream bufferedInputStream = new BufferedInputStream(inputStream);
        DataInputStream dataInputStream = new DataInputStream(bufferedInputStream);

        int i = 0;
        while (dataInputStream.available() &gt; 0) {
            audioData[i] = dataInputStream.readShort();
            i++;
        }

        dataInputStream.close();

        AudioTrack audioTrack = new AudioTrack(
                AudioManager.STREAM_MUSIC, sampleRateInHz,
                AudioFormat.CHANNEL_OUT_MONO,
                AudioFormat.ENCODING_PCM_16BIT,
                bufferSizeInBytes,
                AudioTrack.MODE_STREAM);
        while(audioTrack.getState() != AudioTrack.STATE_INITIALIZED){

        }
        audioTrack.play();
        audioTrack.write(audioData, 0, bufferSizeInBytes);


    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }

}

}
</code></pre>

<p>activity_main.xml</p>

<pre><code>&lt;?xml version="1.0" encoding="utf-8"?&gt;
&lt;LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:orientation="vertical" &gt;

&lt;TextView
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="@string/hello_world" /&gt;
&lt;Button
    android:id="@+id/startrec"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Start Recording Test" /&gt;
&lt;Button
    android:id="@+id/stoprec"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Stop Recording" /&gt;
&lt;Button
    android:id="@+id/playback"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Play Back" /&gt;

&lt;/LinearLayout&gt;
</code></pre>

<p>AndroidManfist.xml permissions</p>

<pre><code>    &lt;uses-permission android:name="android.permission.MODIFY_AUDIO_SETTINGS"/&gt;
    &lt;uses-permission android:name="android.permission.RECORD_AUDIO"/&gt;
    &lt;uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/&gt;
</code></pre>

<p>To Verify if the device works simply play something in the background and  then click <code>Start Recording</code> record a small sector and then click <code>Stop Recording</code> at this point click <code>Play Back</code> and check if you hear the background sound. If you can hear the background sound then AEC is not working. 
But why is this inconsistency occurring, or how do I achieve echo cancellation (I am already using WebRTC within my app for noise cancellation within my apps context) </p>

<p>Any help would be appreciated !</p>