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From: rowe@pender.ee.upenn.edu (Mickey Rowe)
Newsgroups: sci.bio
Subject: Re: Sonar: Bats vs. Dolphins vs. Humans
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Date: 10 May 91 18:39:39 GMT
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In article <9560004@hpfcso.FC.HP.COM> mll@hpfcso.FC.HP.COM (Mark Luce)
     writes: 

>                     Sonar: Bats vs. Dolphins vs. Humans
> 
> In particular, I have
>heard the claim that bats and/or dolphins have certain sonar capabilities
>which we have not as yet been able to duplicate technologically. Is there
>any truth to this, or is this just another modern folk myth?
>----------

I'm not all that aware of research in cetacean echolocation, but a
couple of names that you could look into to find out about bats are N.
(Nabuo?) Suga, and Jim Simmons.  Simmons is probably more along the
lines of what you are looking for, but if you look through the
reference lists of papers by Suga you may find other authors that have
written articles that might interest you.  There was also an article
in Natural History about 2-3 years ago that discussed the history of
how bat sonar was discovered.  It was pretty interesting reading.

As for bats doing things that we can't do, I don't know.  Jim Simmons
has been quoted quite often as having demonstrated that bats can
distinguish the arrival of a sound at each ear when the separation of
that arrival is only 10 nanoseconds! (That's one hundredth of a
millionth of a second...) and that this corresponds to them using
their sonar to recogize the hairs on the legs of a moth (something on
the order of a micrometer).  I wouldn't be at all surprised if it's
true that we don't manufacture devices with that type of resolution,
but I'd be hesitant to suggest that that's because we can't.  I hope
that someone can tell me if this has been accomplished or not, but
back in the mid-80's I heard talk that PET scanners were being
produced with sophisticated enough electronics to measure the
difference in arrival times of photons arising from a single
annihilation event.  For a scanner 1 meter in diameter, that would
require a resolution down to a nanosecond or less in order to be of
any use.

Mickey Rowe    (rowe@pender.ee.upenn.edu)

P.S.  When talking to Walter Heiligenberg (a person who studies
electric fish--another system with incredibly accurate timing) about
Jim Simmons work, he told a group of us that back in the late '40s a
group of people studying crickets disovered that the joint receptors
in their legs can measure displacements down to around 10 angstroms
(that's one nanometer!).  Since that seemed so fantastic, they brought
in Heisenberg--yes, I'm certain :) to check out their equipment, and
he couldn't find anything wrong with it.  Yes, biology is impressive.