public RESULT setCallback(EVENT_CALLBACK callback, EVENT_CALLBACK_TYPE callbackmask = EVENT_CALLBACK_TYPE.ALL)
 {
     return FMOD_Studio_EventInstance_SetCallback(rawPtr, callback, callbackmask);
 }

 private static extern RESULT FMOD_Studio_EventInstance_SetCallback          (IntPtr _event, EVENT_CALLBACK callback, EVENT_CALLBACK_TYPE callbackmask);

            private EVENT_CALLBACK cachedCallback; // cached to prevent gc free-ing the callback delegate

            public EventInstance()
            {
                cachedCallback = wrapperCallback;
            }

 private static extern RESULT FMOD_Studio_EventDescription_SetCallback(IntPtr eventdescription, EVENT_CALLBACK callback, EVENT_CALLBACK_TYPE callbackmask);

 private static extern RESULT FMOD_Event_SetCallback(IntPtr _event, EVENT_CALLBACK callback, IntPtr userdata);

 public RESULT setCallback(EVENT_CALLBACK callback, IntPtr userdata)
 {
     return FMOD_Event_SetCallback(eventraw, callback, userdata);
 }

 public RESULT setCallback(EVENT_CALLBACK callback)
 {
     return FMOD_Studio_EventDescription_SetCallback(rawPtr, callback);
 }

 public static void AddListener(GameObject obj, UGUIEventType evtType, EVENT_CALLBACK<AxisEventData> func)
 {
     AddListenerAsDelegate(obj, evtType, func);
 }