109 lines
5.1 KiB
Plaintext
109 lines
5.1 KiB
Plaintext
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| File Name : ACOUSAMP.ASC | Online Date : 05/09/95 |
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| Contributed by : InterNet | Dir Category : KEELY |
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| From : KeelyNet BBS | DataLine : (214) 324-3501 |
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| A FREE Alternative Sciences BBS sponsored by Vanguard Sciences |
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Two interesting messages about sound and sampling of complex signals.
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Path: news.cc.uch.gr!news.forth.gr!ecrc!Munich.Germany.EU.net!Germany.EU.net!
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EU.net!howland.reston.ans.net!news.moneng.mei.com!uwm.edu!msunews!netnews.
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upenn.edu!b lue.seas.upenn.edu!kisley
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From: kisley@blue.seas.upenn.edu (Michael A Kisley)
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Newsgroups: bionet.neuroscience,alt.sci.physics.acoustics,bionet.audiology
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Subject: acoustic "colors"
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Date: 15 Mar 1995 20:37:51 GMT
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Organization: University of Pennsylvania
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Lines: 52
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Message-ID: <3k7j6v$s0u@netnews.upenn.edu>
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NNTP-Posting-Host: blue.seas.upenn.edu
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X-Newsreader: TIN [version 1.2 PL2-upenn1.3]
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Xref: news.cc.uch.gr bionet.neuroscience:3934 alt.sci.physics.acoustics:193
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I am posting this message in hopes of receiving suggestions/references
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regarding the general topic of auditory "color". However, I would also hope
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that this post might stir up some discussions. This message is cross-posted
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to the following newsgroups:
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bionet.neuroscience
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alt.sci.physics.acoustics
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bionet.audiology
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While doing an introductory review of the topic of echolocation in bats, I
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came across a very interesting idea in a 1990 review paper by G. Neuweiler:
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the idea of echo "colors" in bat echolocation. The general idea behind the
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use of the word "color" is that the bats might be analyzing the spectral
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patterns of the targets which are reflecting their broadband emissions.
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In the general discussion of this review, Neuweiler goes on to hint that
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perhaps this "color" - analysis IS a general feature of auditory systems. His
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reference to humans is that they might perceive acoustical "Gestalt" (grouped
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senses) during speech recognition and when listening to music.
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A somewhat tangential but nevertheless related topic is the use of sonar aids
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for blind people. Apparently there were attempts to use artificial sonar to
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help steer blind people around obstacles.
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However, someone I spoke with was under the impression that the sonar could
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also be used to characterize TEXTURES OF OBJECTS, not unlike the bats' ability
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to characterize targets by their unique spectral pattern.
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These fascinating topics have not been easy to trace, and I would appreciate
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any help people can give me tracking down the following lines:
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1) Has any work been done since 1990 on the idea of echo "colors" in
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echolocating bats (or dolphins)?
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2) Does anyone know of any good, and recent, papers on the topic of
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general auditory "colors" or "Gestalt" (including the areas of
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speech recognition and music-listening)?
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3) Are the sonar aids for the blind still being pursued as a viable
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option, and are there any good references that discuss why/why not?
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Thank you in advance.
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Sincerely,
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Michael Kisley
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Graduate Group of Neuroscience
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University of Pennsylvania
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kisley@eniac.seas.upenn.edu
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Path: news.cc.uch.gr!news.forth.gr!ecrc!Munich.Germany.EU.net!Germany.EU.net!
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EU.net! uunet!in1.uu.net!newstf01.news.aol.com!newsbf02.news.aol.com!not-for-
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mail
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From: gervprado@aol.com (Gervprado)
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Newsgroups: alt.sci.physics.acoustics
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Subject: Re: Help on Periodical signals!
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Date: 16 Mar 1995 20:45:27 -0500
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Organization: America Online, Inc. (1-800-827-6364)
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Lines: 10
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Sender: root@newsbf02.news.aol.com
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Message-ID: <3kapjn$enl@newsbf02.news.aol.com>
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References: <3k12fe$dib@rc1.vub.ac.be>
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Reply-To: gervprado@aol.com (Gervprado)
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NNTP-Posting-Host: newsbf02.mail.aol.com
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Try making a "spectrogram" of the signal. The spectrogram is a three
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dimensional representation of the signal - it's axes are time, frequency and
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amplitude. The easiest way to make one is to take successive FFTs of the
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signal, say once per second.
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After you have accumulated N (where N=the desired number of samples) FFTs and
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computed the magnitude squared of each you will have enough data to make the
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plot which will be in the form of a three dimensional surface or a color (or
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gray scale map).
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The peak of this surface or color map will trace the evolution in time-
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frequency space of your non-stationary periodic signal. Most good signal
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analysis programs, like Matlab have canned routines do do this kind of
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analysis. Good luck!
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