You can create empty objects with the static empty() method of a class, as documented at http://www.mathworks.com/help/techdoc/matlab_oop/brd4btr.html. In this case using "event.listener.empty" as the initial value for the hListener property should work:
properties
hListenerArray = event.listener.empty;
end
An additional comment: if you use the event.listener constructor to create the listeners instead of using addlistener then you will not have to write a delete method because you will have the only reference to them in hListenerArray and they will simply go out of scope and delete themselves when obj is deleted. addlistener is adding an extra reference to the object being listened to and you do not want that in this case.
obj.hListenerArray(end+1) = event.listener(listenObj, listenEvent, callbackFcn);
