code: public void dispose ()
      {
          reclaimAll();
          for (PooledSource pooled : _sources) {
              pooled.source.delete();
          }
          _sources.clear();
  
          // remove from the manager
          _manager.removeGroup(this);
      }
docs: Disposes this sound group, freeing up the OpenAL sources with which it is associated. All
  sounds obtained from this group will no longer be usable and should be discarded.