28 August 2007

Isn't that odd...

In the Land of the Boring and the Waiting (for other people's things to happen) comes the ponderable: Hearing. We learned early on as kids how people (at least with more or less normal hearing) determine where a sound is coming from... that one's brain, through a high-resolution internal timer can tell that the sound arrived at one ear before it arrived at the other, and thus determine whether it is to the left or right of the direction the head is pointed. It's not too much of a stretch to also say that distance can be inferred by the difference in strength of the sound. i.e. If the sound is far away, the difference in distance between your ears is small, so they should hear it the same. But if it's close, the distance between your ears is more significant and the softening of the sound over that distance is noticeable.

But what about front to back and up and down? In this model, ears are point receivers and there's only two of them. There's a plane of symmetry, and since we can't rotate the fleshy flap of our outer ear (like a deer) a sound in front should sound roughly the same as the sound in back. So how do we know? Surely you can tell when a sound is in front or back, right? So how do we do it? Any audiologists out there want to shed some light on the matter?


And then there was this... Windows apparently eating itself.


Ah, the circle of life.

1 comment:

Anonymous said...

The fore aft position determination would almost have to be some sort of effect of the shape of the ear cannal/inner ear. I am at a bit of a loss as to how the passages of the ear could do this, but hey; the survival of the fittest is (used to be for humans in the western world) a damn powerfull thing.

also: http://en.wikipedia.org/wiki/Sound_localization