auEvent.mEventType = kAudioUnitEvent_PropertyChange;
        auEvent.mArgument.mProperty.mAudioUnit = mAU;
        auEvent.mArgument.mProperty.mPropertyID = kAudioUnitMyCustomProperty;
        auEvent.mArgument.mProperty.mScope = kAudioUnitScope_Global;
        auEvent.mArgument.mProperty.mElement = 0;
        verify_noerr (AUEventListenerAddEventType (mAUEventListener, self, &auEvent));