acoustic "colors"

Michael A Kisley kisley at
Wed Mar 15 15:37:51 EST 1995

I am posting this message in hopes of receiving suggestions/references
regarding the general topic of auditory "color".  However, I would also
hope that this post might stir up some discussions.  This message is
cross-posted to the following newsgroups:


While doing an introductory review of the topic of echolocation in bats,
I came across a very interesting idea in a 1990 review paper by G.
Neuweiler:  the idea of echo "colors" in bat echolocation.  The general
idea behind the use of the word "color" is that the bats might be
analyzing the spectral patterns of the targets which are reflecting
their broadband emissions.

In the general discussion of this review, Neuweiler goes on to hint that
perhaps this "color"-analysis is a general feature of auditory systems.
His reference to humans is that they might perceive acoustical "Gestalt"
during speech recognition and when listening to music.

A somewhat tangential but nevertheless related topic is the use of
sonar aids for blind people.  Apparently there were attempts to use
artificial sonar to help steer blind people around obstacles.  However,
someone I spoke with was under the impression that the sonar could also
be used to characterize textures of objects, not unlike the bats'
ability to characterize targets by their unique spectral pattern.

These fascinating topics have not been easy to trace, and I would appreciate
any help people can give me tracking down the following lines:

1)  Has any work been done since 1990 on the idea of echo "colors" in
    echolocating bats (or dolphins)?

2)  Does anyone know of any good, and recent, papers on the topic of
    general auditory "colors" or "Gestalt" (including the areas of
    speech recognition and music-listening)?

3)  Are the sonar aids for the blind still being pursued as a viable
    option, and are there any good references that discuss why/why not?

Thank you in advance.

Michael Kisley
Graduate Group of Neuroscience
University of Pennsylvania
kisley at

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