спрете фоновия звук на аудио плейъра на Android

Възпроизвеждам звук в дейността на аудиоплейъра на Android. когато поставя на пауза тази дейност, звукът продължава да се възпроизвежда във фонов режим. Искам да спра този звук, когато възобновя тази дейност на аудиоплейъра. ето моят код.. може ли някой да ми помогне как мога да направя това. всяка помощ ще бъде много ценена, благодаря :)

public class AndroidBuildingMusicPlayerActivity extends Activity implements
        OnCompletionListener, SeekBar.OnSeekBarChangeListener {

    private ImageButton btnPlay;
    private ImageButton btnForward;
    private ImageButton btnBackward;
    // private ImageButton btnNext;
    // private ImageButton btnPrevious;
    // private ImageButton btnPrevious;
    private ImageButton btnPlaylist;
    private ImageView songimg;
    // private ImageButton btnRepeat;
    // private ImageButton btnShuffle;
    private SeekBar songProgressBar;
    private TextView songTitleLabel;
    private TextView songCurrentDurationLabel;
    private TextView songTotalDurationLabel;
    // Media Player
    private MediaPlayer mp;
    // Handler to update UI timer, progress bar etc,.
    private Handler mHandler = new Handler();;
    private SongsManager songManager;
    private Utilities utils;
    private int seekForwardTime = 5000; // 5000 milliseconds
    private int seekBackwardTime = 5000; // 5000 milliseconds
    private int currentSongIndex = 0;
    private boolean isShuffle = false;
    private boolean isRepeat = false;
    private ArrayList<HashMap<String, String>> songsList = new ArrayList<HashMap<String, String>>();
    String[] stringArray = new String[4];

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mediaplayer);

        // All player buttons
        btnPlay = (ImageButton) findViewById(R.id.btnPlay);
        btnForward = (ImageButton) findViewById(R.id.btnForward);
        btnBackward = (ImageButton) findViewById(R.id.btnBackward);
        // btnNext = (ImageButton) findViewById(R.id.btnNext);
        // btnPrevious = (ImageButton) findViewById(R.id.btnPrevious);
        btnPlaylist = (ImageButton) findViewById(R.id.btnPlaylist);
        songimg = (ImageView) findViewById(R.id.songimg);
        // btnShuffle = (ImageButton) findViewById(R.id.btnShuffle);
        btnPlaylist = (ImageButton) findViewById(R.id.btnPlaylist);
        songProgressBar = (SeekBar) findViewById(R.id.songProgressBar);
        songTitleLabel = (TextView) findViewById(R.id.songTitle);
        songCurrentDurationLabel = (TextView) findViewById(R.id.songCurrentDurationLabel);
        songTotalDurationLabel = (TextView) findViewById(R.id.songTotalDurationLabel);

        // Mediaplayer
        mp = new MediaPlayer();
        songManager = new SongsManager();
        utils = new Utilities();

        // Listeners
        songProgressBar.setOnSeekBarChangeListener(this); // Important
        mp.setOnCompletionListener(this); // Important

        // Getting all songs list
        songsList = songManager.getPlayList();
        final String[] stringArray = getIntent().getStringArrayExtra("string-array");
        // By default play first song
        playSong(stringArray[0]);
        songTitleLabel.setText(stringArray[1]);
        new DownloadImageTask(songimg).execute(stringArray[2]);
        btnPlaylist.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                final String[] option = new String[] {"Share",
                        "Stop" };
                ArrayAdapter<String> adapters = new ArrayAdapter<String>(
                        AndroidBuildingMusicPlayerActivity.this,
                        android.R.layout.select_dialog_item, option);
                AlertDialog.Builder builder = new AlertDialog.Builder(
                        AndroidBuildingMusicPlayerActivity.this);
                builder.setTitle("Choose Action");
                builder.setAdapter(adapters,
                        new DialogInterface.OnClickListener() {

                            public void onClick(DialogInterface dialog,
                                    int which) {
                                // TODO Auto-generated method stub

                                if (which == 1) {
                                    mp.stop();
                                    finish();
                                }
                                if (which == 0) {
                                    Intent browserIntent = new Intent(
                                            Intent.ACTION_SEND);
                                    browserIntent.setType("text/plain");
                                    browserIntent.putExtra(
                                            android.content.Intent.EXTRA_TEXT,
                                            stringArray[3]);
                                    // ,
                                    // Uri.parse("https://www.youtube.com/watch?v="+ids.get(mPosition)));
                                    startActivity(Intent.createChooser(
                                            browserIntent, "Share Song Link"));
                                }
                            }
                        });
                final AlertDialog dialog = builder.create();
                dialog.show();
            }
        });
        /**
         * Play button click event plays a song and changes button to pause
         * image pauses a song and changes button to play image
         * */
        btnPlay.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // check for already playing
                if (mp.isPlaying()) {
                    if (mp != null) {
                        mp.pause();
                        // Changing button image to play button
                        btnPlay.setImageResource(R.drawable.btn_play);
                    }
                } else {
                    // Resume song
                    if (mp != null) {
                        mp.start();
                        // Changing button image to pause button
                        btnPlay.setImageResource(R.drawable.btn_pause);
                    }
                }

            }
        });

        /**
         * Forward button click event Forwards song specified seconds
         * */
        btnForward.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // get current song position
                int currentPosition = mp.getCurrentPosition();
                // check if seekForward time is lesser than song duration
                if (currentPosition + seekForwardTime <= mp.getDuration()) {
                    // forward song
                    mp.seekTo(currentPosition + seekForwardTime);
                } else {
                    // forward to end position
                    mp.seekTo(mp.getDuration());
                }
            }
        });

        /**
         * Backward button click event Backward song to specified seconds
         * */
        btnBackward.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View arg0) {
                // get current song position
                int currentPosition = mp.getCurrentPosition();
                // check if seekBackward time is greater than 0 sec
                if (currentPosition - seekBackwardTime >= 0) {
                    // forward song
                    mp.seekTo(currentPosition - seekBackwardTime);
                } else {
                    // backward to starting position
                    mp.seekTo(0);
                }

            }
        });



    }

    /**
     * Receiving song index from playlist view and play the song
     * */
    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);
        if (resultCode == 100) {
            currentSongIndex = data.getExtras().getInt("songIndex");
            // play selected song
            playSong(stringArray[0]);
        }

    }

    /**
     * Function to play a song
     * 
     * @param songIndex
     *            - index of song
     * */
    public void playSong(String songpath) {
        // Play song
        try {
            mp.reset();
            mp.setDataSource(songpath);
            mp.prepare();
            mp.start();
            // Displaying Song title
            // String songTitle = songsList.get(songIndex).get("songTitle");
            // songTitleLabel.setText(songTitle);

            // Changing Button Image to pause image
            btnPlay.setImageResource(R.drawable.btn_pause);

            // set Progress bar values
            songProgressBar.setProgress(0);
            songProgressBar.setMax(100);

            // Updating progress bar
            updateProgressBar();
        } catch (IllegalArgumentException e) {
            e.printStackTrace();
        } catch (IllegalStateException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * Update timer on seekbar
     * */
    public void updateProgressBar() {
        mHandler.postDelayed(mUpdateTimeTask, 100);
    }

    /**
     * Background Runnable thread
     * */
    private Runnable mUpdateTimeTask = new Runnable() {
        public void run() {
            long totalDuration = mp.getDuration();
            long currentDuration = mp.getCurrentPosition();

            // Displaying Total Duration time
            songTotalDurationLabel.setText(""
                    + utils.milliSecondsToTimer(totalDuration));
            // Displaying time completed playing
            songCurrentDurationLabel.setText(""
                    + utils.milliSecondsToTimer(currentDuration));

            // Updating progress bar
            int progress = (int) (utils.getProgressPercentage(currentDuration,
                    totalDuration));
            // Log.d("Progress", ""+progress);
            songProgressBar.setProgress(progress);

            // Running this thread after 100 milliseconds
            mHandler.postDelayed(this, 100);
        }
    };

    /**
     * 
     * */
    @Override
    public void onProgressChanged(SeekBar seekBar, int progress,
            boolean fromTouch) {

    }

    /**
     * When user starts moving the progress handler
     * */
    @Override
    public void onStartTrackingTouch(SeekBar seekBar) {
        // remove message Handler from updating progress bar
        mHandler.removeCallbacks(mUpdateTimeTask);
    }

    /**
     * When user stops moving the progress hanlder
     * */
    @Override
    public void onStopTrackingTouch(SeekBar seekBar) {
        mHandler.removeCallbacks(mUpdateTimeTask);
        int totalDuration = mp.getDuration();
        int currentPosition = utils.progressToTimer(seekBar.getProgress(),
                totalDuration);

        // forward or backward to certain seconds
        mp.seekTo(currentPosition);

        // update timer progress again
        updateProgressBar();
    }

    /**
     * On Song Playing completed if repeat is ON play same song again if shuffle
     * is ON play random song
     * */
    @Override
    public void onCompletion(MediaPlayer arg0) {

        // check for repeat is ON or OFF
        if (isRepeat) {
            // repeat is on play same song again
            playSong(stringArray[0]);
        } else if (isShuffle) {
            // shuffle is on - play a random song
            Random rand = new Random();
            currentSongIndex = rand.nextInt((songsList.size() - 1) - 0 + 1) + 0;
            playSong(stringArray[0]);
        } else {
            // no repeat or shuffle ON - play next song
            if (currentSongIndex < (songsList.size() - 1)) {
                playSong(stringArray[0]);
                currentSongIndex = currentSongIndex + 1;
            } else {
                // play first song
                playSong(stringArray[0]);
                currentSongIndex = 0;
            }
        }
    }

    @Override
    public void onDestroy() {
        super.onDestroy();
        //mp.stop();
    }

    class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
        ImageView bmImage;

        public DownloadImageTask(ImageView bmImage) {
            this.bmImage = bmImage;
        }

        @Override
        protected void onPreExecute() {
            // TODO Auto-generated method stub
            super.onPreExecute();
            // pd.show();
        }

        protected Bitmap doInBackground(String... urls) {
            String urldisplay = urls[0];
            Bitmap mIcon11 = null;
            try {
                InputStream in = new java.net.URL(urldisplay).openStream();
                mIcon11 = BitmapFactory.decodeStream(in);
            } catch (Exception e) {
                Log.e("Error", e.getMessage());
                e.printStackTrace();
            }
            return mIcon11;
        }

        @Override
        protected void onPostExecute(Bitmap result) {
            super.onPostExecute(result);
            // pd.dismiss();
            bmImage.setImageBitmap(result);
        }
    }
}