code: private int findFreeSource() {
  		for (int i=1;i<sourceCount-1;i++) {
  			int state = AL10.alGetSourcei(sources.get(i), AL10.AL_SOURCE_STATE);
  			
  			if ((state != AL10.AL_PLAYING) && (state != AL10.AL_PAUSED)) {
  				return i;
  			}
  		}
  		
  		return -1;
  	}
docs: Find a free sound source
  
  @return The index of the free sound source