code: public void setEnabled (final SoundType type, final boolean enabled)
      {
          boolean changed;
          if (enabled) {
              changed = _disabledTypes.remove(type);
          } else {
              changed = _disabledTypes.add(type);
          }
          if (changed) {
              _enabledObservers.apply(new ObserverOp<SoundEnabledObserver>() {
                  public boolean apply (SoundEnabledObserver observer) {
                      observer.enabledChanged(type, enabled);
                      return true;
                  }
              });
          }
      }
docs: Turns on or off the specified sound type.