Android : How to change background image when mediaplayer button pressed?

I have done a simple media player and I would like to ask.. how it be possible to change background image when mediaplayer button is pressed, and when I release the button, background image returns to original. I would like to make image effect when press mediaplayer button.

This is my code i use for mp:

public class MainActivity extends ActionBarActivity {

private MediaPlayer mp;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    mp = new MediaPlayer();
}

public void btn1 (View v){
    mp.release();
    mp = MediaPlayer.create(this, R.raw.est1);
    mp.start();

}

    @Override
      public void onDestroy()
      {
           if (mp != null) {
               mp.release();
               mp = null; 
              }
         super.onDestroy();
      }



}