+ event.mEventType = kAudioUnitEvent_BeginParameterChangeGesture;
+ event.mArgument.mParameter.mAudioUnit = unit->AU();
+ event.mArgument.mParameter.mParameterID = descriptors[param_id].id;
+ event.mArgument.mParameter.mScope = descriptors[param_id].scope;
+ event.mArgument.mParameter.mElement = descriptors[param_id].element;
+
+ if (AUEventListenerRemoveEventType (_parameter_listener, _parameter_listener_arg, &event) != noErr) {
+ return -1;
+ }
+
+ event.mEventType = kAudioUnitEvent_EndParameterChangeGesture;
+ event.mArgument.mParameter.mAudioUnit = unit->AU();
+ event.mArgument.mParameter.mParameterID = descriptors[param_id].id;
+ event.mArgument.mParameter.mScope = descriptors[param_id].scope;
+ event.mArgument.mParameter.mElement = descriptors[param_id].element;
+
+ if (AUEventListenerRemoveEventType (_parameter_listener, _parameter_listener_arg, &event) != noErr) {
+ return -1;
+ }
+