If you alter the Talker class, or preferably subclass it, you can theoretically animate as many parts as you want. Of course, if you don't actually have support for a fourth (or fifth, sixth...) portrait part, of course characterEars gets ignored.
Assuming for a second you correctly implement your specific characters' talkers as subclasses of Talker, you'll notice if you look at the Talker class' init that it indeed takes only three parameters: theBust, theEyes, and theMouth. And the class' properties include the same trio without the article. Then in the show method, each of these (if set) is drawn, and in doit they are cycled. And of course in dispose each of the three parts are disposed of.
So if you want your characters to support animated ears, you'll want to adapt each of these methods in Talker (or again preferably a subclass) accordingly.