TarsosDSP PitchDetection Issue

Question

I am using the audiodispatcher from the TarsosDSPlibrary.

The pitchdetection is used to detect sounds from the mic. Once detected, it switches to the next activity (which is a Maths quiz). After completing the quiz on the next activity, it returns to this activity and starts the process all over again.

What is bugging me is that my APP is working 90% of the time when using the pitchdetection function. However, sometimes it doesn't work and throws an error as follows:

E/AudioRecord: start() status -38

and the app no longers switches to the next activity.

package com.humanfactorsandappliedcognitionlab.research.mathsapp;

import android.content.Context;
import android.content.DialogInterface;
import android.media.MediaPlayer;
import android.os.AsyncTask;
import android.os.IBinder;
import android.speech.tts.TextToSpeech;
import android.speech.tts.UtteranceProgressListener;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.Intent;

import java.util.HashMap;
import java.util.Locale;
import java.util.concurrent.RunnableFuture;

import be.tarsos.dsp.AudioDispatcher;
import be.tarsos.dsp.AudioEvent;
import be.tarsos.dsp.io.android.AudioDispatcherFactory;
import be.tarsos.dsp.pitch.PitchDetectionHandler;
import be.tarsos.dsp.pitch.PitchDetectionResult;
import be.tarsos.dsp.pitch.PitchProcessor;

public class MainActivity extends AppCompatActivity implements TextToSpeech.OnInitListener {

MediaPlayer notifySound;
MediaPlayer endSound;

AudioDispatcher dispatcherMAIN;
PitchProcessor pitchProcessorMAIN;
public boolean isListening = false;

TextToSpeech tts;

private int sensitivity = 100;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    notifySound = MediaPlayer.create(this, R.raw.samsung);
    endSound = MediaPlayer.create(this, R.raw.ding);

    OPTION = dbHandler.getOPTION();

    tts = new TextToSpeech(this, this);
    tts.setOnUtteranceProgressListener(new UtteranceProgressListener() {
        @Override
        public void onStart(String utteranceId) {
            runOnUiThread(new Runnable() {
                @Override
                public void run(){

                }
            });
        }

        @Override
        public void onDone(String utteranceId) {
            runOnUiThread(new Runnable() {
                @Override
                public void run(){

                    startListenToTalk();
                }
            });
        }

        @Override
        public void onError(String utteranceId) {

        }
    });

}

private void speakOut() {
    Log.e("TTS", "SPEAKING...");
    String text = "Please  Say  Continue  to  Proceed  ";
    HashMap<String, String> map = new HashMap<String, String>();
    map.put(TextToSpeech.Engine.KEY_PARAM_UTTERANCE_ID, "");
    tts.speak(text, TextToSpeech.QUEUE_FLUSH, map);
}

private void startListenToTalk() {
    dispatcherMAIN = AudioDispatcherFactory.fromDefaultMicrophone(22050, 1024, 0);
    pitchProcessorMAIN = new PitchProcessor(PitchProcessor.PitchEstimationAlgorithm.FFT_YIN, 22050, 1024, new PitchDetectionHandler() {
        @Override
        public void handlePitch(PitchDetectionResult pitchDetectionResult,
                                AudioEvent audioEvent) {

            final float pitchInHz = pitchDetectionResult.getPitch();

            runOnUiThread(new Runnable() {
                @Override
                public void run() {

                    ImageButton buttonOK = (ImageButton) findViewById(R.id.buttonOK);
                    TextView textINPUT = (TextView)findViewById(R.id.textINPUT);
                    if (pitchInHz > sensitivity) {
                        Log.e("pitch : ", pitchInHz + "");
                        if (isListening) {
                            try {
                                dispatcherMAIN.stop();
                                Intent gotoMaths = new Intent(MainActivity.this, MathsActivity.class);
                                startActivity(gotoMaths);
                            } catch (Exception e) {
                                e.printStackTrace();
                            }
                        }
                    }
                }
            });
        }
    });

    dispatcherMAIN.addAudioProcessor(pitchProcessorMAIN);
    new Thread(dispatcherMAIN, "Audio Dispatcher").start();
    isListening = true;
}

@Override
protected void onPause() {
    super.onPause();

    if (notifySound != null) {
        notifySound.release();
    }

    if (endSound != null) {
        endSound.release();
    }

    if (isListening) {
        try {
            dispatcherMAIN.stop();
        } catch (Exception e) {
            e.printStackTrace();
        }
        isListening = false;
    }

    finish();
}

@Override
public void onStop(){
    super.onStop();

    if (tts != null) {
        tts.shutdown();
    }
}

@Override
public void onInit(int status) {
    if (status == TextToSpeech.SUCCESS) {
        int result = tts.setLanguage(Locale.US);
        if (result == TextToSpeech.LANG_MISSING_DATA
                || result == TextToSpeech.LANG_NOT_SUPPORTED) {
            Log.e("TTS", "This Language is not supported");
        } else {
                if(OPTION == "3") {
                    speakOut();
                }
        }
    } else {
        Log.e("TTS", "Initilization Failed!");
    }
}