Vision/Hearing Symmetries (Bradley Wood Libbey )

Subject: Vision/Hearing Symmetries
From:    Bradley Wood Libbey  <gt1556a(at)PRISM.GATECH.EDU>
Date:    Wed, 12 Jul 2000 19:16:25 -0400

Michael Kubovy and List,

        Although I can not assist you in finding a reference, if you are
thinking about sensing reflected light/sound I hope the following will be
of benefit.

        The visual system has a large number of sensors, rods and cones,
even with one eye closed.  Combined with the lens, a highly developed
diffractor, many reflections can be determined with a high spatial
resolution.  (Reflections and sources are similar, for example your
computer screen is a source while sonar utilizes reflections.)

The auditory system on the other hand has only two spatial sensors with a
less than perfect diffractor, the outer ear, head, and shoulders.
Therefore its spatial resolution is quite poor for more than a couple of
simultaneous reflections. (Consider the thousands of image sources in a
room.)

Instead the auditory system uses its exceptional temporal abilities to
compensate for its inefficiencies spatially.  Time delays between ears and
frequency content account for much of our localization abilities. In the
other system, light is entirely too fast for any temporal information
between eyes.  Continuing further the eyes have poor frequency resolution
with only three or four frequency sensors; the ear has the basilar
membrane, I dare not say more.

Hope you found this interesting.

Brad Libbey
Georgia Institute of Technology
gt1556a(at)prism.gatech.edu