SensorEventListener lightSensorEventListener
    = new SensorEventListener(){
..
public void onSensorChanged(SensorEvent arg0) {
..
 if(start == true){
		   if(arg0.values[0] < Threshold){
			    float actualVolume = (float) audioManager.getStreamVolume(AudioManager.STREAM_MUSIC);
	   			float maxVolume = (float) audioManager.getStreamMaxVolume(AudioManager.STREAM_MUSIC);
	   			float volume = actualVolume / maxVolume;
	   			// Is the sound loaded already?
	   			if (loaded) {
	   				soundPool.play(soundID, volume, volume, 1, 0, 1f);
	   				Log.e("Test", "Played sound");
	   			}
	   		}
	   }else{
		   
	   }
	   
   }};

boolean completed = true;
MediaPlayer mMediaPlayer;

 @Override
   public void onCreate(Bundle savedInstanceState) {
...
//MEDIAPLAYER
		mMediaPlayer = MediaPlayer.create(this, R.raw.alarm_1);
		mMediaPlayer.setLooping(false);
		mMediaPlayer.setOnCompletionListener(complete);
}
//Listener wenn Song vorbei ;)
private OnCompletionListener complete = new OnCompletionListener(){
	   public void onCompletion(MediaPlayer arg0){
		   completed =  true;
	   }
   };
//z.b. beim Button event
private OnClickListener btListener = new OnClickListener()
   {
   	public void onClick(View v){   	
   		
   		if(completed){   		
   		mMediaPlayer.start();
   		completed = false;
   		}
           }
};