interrupted audio track

test.java

package com.example.jchang.helloworld;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.LinearLayout;
import android.util.Log;

import com.opentok.android.Publisher;
import com.opentok.android.PublisherKit;
import com.opentok.android.Session;
import com.opentok.android.Stream;
import com.opentok.android.Subscriber;
import com.opentok.android.SubscriberKit;
import com.opentok.android.OpentokError;

import android.speech.tts.TextToSpeech;

public class MainActivity extends AppCompatActivity implements Session.SessionListener,
        Publisher.PublisherListener, Subscriber.SubscriberListener,
        Subscriber.VideoListener {

    public static final String API_KEY = "";
    public static final String SESSION_ID = "";
    public static final String TOKEN = "";
    public static final String LOGTAG = MainActivity.class.getName();
    private TextToSpeech textToSpeech;

    private LinearLayout publisherView;
    private LinearLayout.LayoutParams publisherParams;
    private LinearLayout subscriberView;
    private LinearLayout.LayoutParams subscriberParams;

    private class GixoSession extends Session {
        private GixoSession() {
            super(getBaseContext(), API_KEY, SESSION_ID);
        }

        @Override
        public void onConnected() {
            try {
                Thread.sleep(2500);
                Publisher publisher = new Publisher.Builder(getBaseContext()).videoTrack(false).audioTrack(true).build();
                publish(publisher);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }

        }
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        textToSpeech = new TextToSpeech(getBaseContext(), new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(int status) {
                if(status == TextToSpeech.SUCCESS) {
                    textToSpeech.speak("one two three four five six seven eight nine ten eleven twelve thirteen fourteen fifteen sixteen", TextToSpeech.QUEUE_FLUSH, null);
                }
            }
        });

        GixoSession session = new GixoSession();
        session.connect(TOKEN);

    }

    @Override
    public void onConnected(Session session) {
        Log.i(LOGTAG, "call to onConnected of the SessionListener");
        Publisher publisher = new Publisher(MainActivity.this);
        publisher.setPublisherListener(this);
        publisherView.addView(publisher.getView(), publisherParams);
        session.publish(publisher);
    }

    @Override
    public void onStreamReceived(Session session, Stream stream) {
        Log.i(LOGTAG, "call to onStreamReceived");
        Subscriber subscriber = new Subscriber(MainActivity.this, stream);
        subscriber.setVideoListener(this);
        session.subscribe(subscriber);
        subscriberView.addView(subscriber.getView(), subscriberParams);
    }

    @Override
    public void onDisconnected(Session session) {
        Log.i(LOGTAG, "call to onDisconnected of the SessionListener");
    }

    @Override
    public void onStreamDropped(Session session, Stream stream) {
        Log.i(LOGTAG, "call to onStreamDropped of the SessionListener");
    }

    @Override
    public void onError(Session session, OpentokError error) {
        Log.i(LOGTAG, "SessionListener error: " + error.getMessage());
    }

    @Override
    public void onStreamCreated(PublisherKit publisher, Stream stream) {
        Log.i(LOGTAG, "call to onStreamCreated of the PublisherListener");
    }

    @Override
    public void onStreamDestroyed(PublisherKit publisher, Stream stream) {
        Log.i(LOGTAG, "call to onStreamDestroyed of the PublisherListener");
    }

    @Override
    public void onError(PublisherKit publisher, OpentokError error) {
        Log.i(LOGTAG, "PublisherListener error: " + error.getMessage());
    }

    @Override
    public void onConnected(SubscriberKit subscriber) {
        Log.i(LOGTAG, "call to onConnected of the SubscriberListener");
    }

    @Override
    public void onDisconnected(SubscriberKit subscriber) {
        Log.i(LOGTAG, "call to onDisconnected of the SubscriberListener");
    }

    @Override
    public void onError(SubscriberKit subscriber, OpentokError error) {
        Log.i(LOGTAG, "SubscriberListener error: " + error.getMessage());
    }

    @Override
    public void onVideoDataReceived(SubscriberKit subscriber) {
        Log.i(LOGTAG, "call to onVideoDataReceived of the VideoListener");
    }

    @Override
    public void onVideoDisabled(SubscriberKit subscriber, java.lang.String reason) {
        Log.i(LOGTAG, "call to onVideoDisabled of the VideoListener");
    }

    @Override
    public void onVideoEnabled(SubscriberKit subscriber, java.lang.String reason) {
        Log.i(LOGTAG, "call to onVideoEnabled of the VideoListener");
    }

    @Override
    public void onVideoDisableWarning(SubscriberKit subscriber) {
        Log.i(LOGTAG, "call to onVideoDisableWarning of the VideoListener");
    }

    @Override
    public void onVideoDisableWarningLifted(SubscriberKit subscriber) {
        Log.i(LOGTAG, "call to onVideoDisableWarning of the VideoListener");
    }

}