While an interesting read, this does not address the vertical aspect of the sound reaching a person. Say I am standing next to a person sitting down. The person sitting down is in the optimal position to listen to speakers placed at a 45 degree angle. I am standing next to that person, perhaps 2-3 feet above their ear level. I am benefitting less from the sound than they are. I experienced this with my 2 Pi Towers the other day as my wife was seated in the optimal position while I stood next to her. Not that what I heard was unpleasant, but it was far from optimal.