(he wore earphones connected to a computer - Snoopy sitting on top of his kennel pretending to be the Red Baron came to mind!)

Good point about some dogs being deaf in one ear only.

Also Margaret, those are also great points. Leo has always had that difficulty picking out directional sound and I trained him to recall to a shout and a waving motion of the arms or else he will run off after other people -- though he has no problem hearing at short range.