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From: davidh@uhunix1.uhcc.Hawaii.Edu (David A. Helweg)
Newsgroups: sci.bio
Subject: Re: Sonar: Bats vs. Dolphins vs. Humans
Summary: cetacean references
Message-ID: <12987@uhccux.uhcc.Hawaii.Edu>
Date: 12 May 91 02:57:53 GMT
References: <9560004@hpfcso.FC.HP.COM>
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In article <9560004@hpfcso.FC.HP.COM> mll@hpfcso.FC.HP.COM (Mark Luce) writes:
>/ hpfcso:sci.misc / mll@hpfcso.FC.HP.COM (Mark Luce) /  4:53 pm  May  3, 1991 /
>                     Sonar: Bats vs. Dolphins vs. Humans
> 
>     I am interested in any comparisons of the sonar capabilities of bats,
>dolphins, and humans (human technology, of course!). 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?
>----------

Current knowledge of bat echolocation indicates that bats can resolve differ-
ences in timing (temporal resolution) down around 10 ns, a distance of about
.35 microns.  The temporal discrimination abilitites of echolocating dolphins
is currently thought to be about 50 ns, which corresponds to about .31 microns
in salt water. We human beings certainly have invented acoustic equipment that
is capable of operating at such high speeds (such as multi-gigaHz sampling with
digital oscilloscopes).  Currently, however, I think that our SONAR capabil-
ities _are_ limited.  I don't know much about SONAR systems and I'd bet the
engineers who work with stuff like side-scan SONAR would take issue with my
assertion.  Right now, our SONAR applications have only required coarse resolu-
tion.

I recommend three (big) books that deal with all aspects of echolocation and
animal SONAR.
Busnel, R-G. & Fish, J.F. (eds.) 1980. Animal Sonar Systems. NATO Advanced
  Study Institutes Series Vol. 28. New York: Plenum Press.
Nachtigall, P.E. & Moore, P.W.B. (eds.) 1988.  Animal Sonar: Processes and
  Performance. NATO Advanced Study Institutes Series Vol 156. New York:
  Plenum Press.
Thomas, J.A. & Kastelein, R.A. (eds.) 1991. Sensory Abilities of Cetaceans: 
  Laboratory and Field Evidence.  NATO ASI Series Vol. 196. New York: Plenum.

---
these volumes contain an enormous amount of information both about bat and
dolphin echolocation.  One of the most interesting things to us dolphin
echolocation researchers is the _difference_ between the performance of bats
and dolphins, set up in part by the 4-fold increase in speed of sound from
air to water, and in part by the ecology of the different taxa.