Eric:
Our brain post processes signals, which is a combination of information of different senses. As such there are optical and auditive illusions. We can hear and see things which are physically not existant, just because our brain concludes they are there, or ought to be there within those specific circumstances.
An example of two senses combining like that from home theatre is where to place the center channel speaker.
Humans, possibly due to a pre-historic need to hunt small animals, are very good at locating by sound alone things that are lower than our heads. Humans are not very good at all at locating things by sound alone that are higher than our heads.
Thus the center channel speaker should be placed either behind an acoustically transparent movie screen or above it. If behind the screen then the audio clues are enough to locate the action. If the speaker is above the screen then the brain can't tell where the sound is coming from, but it sees the car chase on the screen, and the brain convinces the listener that the sound is coming from several feet lower than it really is.
I would imagine that a bat, who has to fly under objects like tree branches, or quick moving small insects (food), is better at locating things above them than we are. A bat's ears have a complex collection of folds that help it determine an insect's vertical position.
Room size is determined by the
time of the
first echo, and although a diffuser may make it quieter, and knock the sound around the room, some of the echo is coming right back at ya, and that's how a bat would know how big the room is. A diffuser would have little effect on that perception. Bats are pretty good at muliple echoes, and with two ears are able to determine where the object is, how big it is and in what direction it is moving. An absorber or diffuser might make the bat think the wall is smaller than it really is, but not further away.