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Re: Implicit human echolocation

yes, the blindfold would substantially alter the HRTF. As a sighted
person, I still hate wearing any clothing with a hood (even if it isn't
noisy), or even a high collar (e.g sheepskin jacket with collar up).
I've even wondered wether wearing glasses interferes - it seems so to
me, though that may simply be because I'm not a regular glasses wearer -
I don't quite know if this is actually a psychoacoustic effect. Of
course, most of these effects would be on high frequencies.


Dr. Peter Lennox
Signal Processing Applications Research Group
University of Derby
Int. tel: 3155
>>> Thomas G Brennan <g_brennantg@xxxxxxxxxxxxxxx> 06/01/07 5:08 AM >>>
Facial vision is a term which is no longer used as the face has nothing,
itself, to do with echo location.  However, as a long time user of echo
for everything from bike riding to skydiving I can tell you that
covering the
face as with a blindfold does effect echo location (especially passive
because it changes the texture and echo characteristics of the face.  A
situation is seen in either enucleation or eviseration particularly when
eyes are involved.  So far as I know, the type of implant used makes no
difference as is the case with the type of prosthetic since materials
such as
glass, granet, etc. are no longer used.


Tom Brennan  KD5VIJ, CCC-A/SLP
web page http://titan.sfasu.edu/~g_brennantg/sonicpage.html

On Thu, 31 May 2007, Harry Erwin wrote:

> Date: Thu, 31 May 2007 08:50:37 +0100
> From: Harry Erwin <harry.erwin@xxxxxxxxxxxxxxxx>
> To: AUDITORY@xxxxxxxxxxxxxxx
> Subject: Re: Implicit human echolocation
> The phenomenon is known as facial vision. Dr. Lawrence Scadden could
> do it well enough to ride a bicycle in traffic despite his total
> blindness. He was a participant in at least one published study.
> Most people who use it use passive echolocation as schools for the
> blind discouraged their students in the past from making echolocation
> sounds. Humans can also use active echolocation, but not with the
> range accuracy of bats. I've used passive echolocation. Sighted
> humans are about as accurate as bats in azimuth and elevation.
> It's effortful. Once you've memorised your environment, you prefer to
> operate by dead reckoning, which means you don't notice changes
> unless they're obvious. This phenomenon is also seen in bats and
> rodents, and Don Griffin discussed it in Listening in the Dark.
> --
> Harry Erwin, PhD, Senior Lecturer of Computing, University of
> Sunderland. Computational neuroethologist:
> http://scat-he-g4.sunderland.ac.uk/~harryerw/phpwiki/index.php/
> AuditoryResearch

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