code: public static SoundManager createSoundManager (RunQueue rqueue)
      {
          if (_soundmgr != null) {
              throw new IllegalStateException("A sound manager has already been created.");
          }
          _soundmgr = new SoundManager(rqueue);
          return _soundmgr;
      }
docs: Creates, initializes and returns the singleton sound manager instance.
  
  @param rqueue a queue that the sound manager can use to post short runnables that must be
  executed on the same thread from which all other sound methods will be called.