Unfortunately, since Jon wished that no one could hear his voice, no one could hear the wish that was made. And since the stone could only affect people within a few miles of it, the wish he made over the radio would only affect people in Jon's town and a bit of the outskirts.
So, in other words, it wasn't any different than if Jon just said the wish to himself ... except that he couldn't hear his own voice, since that was part of his previous wish. The change would happen, but no one would think it was strange or out of the ordinary, and thanks to Jon's "no one hears my voice" wish, Jon wouldn't find it out of the ordinary either. As far as he knew now, men and women (at least in his town, for some reason) had always had the same sexual organs.
Meanwhile, at Karyn's house ...
