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Fw: The ear thing.

Ron Blue rcb5 at msn.com
Thu Jan 15 11:35:35 EST 1998


Gabe has raised some interesting questions and my opinion supports his.
Could we have some guidance on this question.
Ron Blue
>>>>
-----Original Message-----
From: Gabe Velez <gvelez at richmond.infi.net>
To: Ron Blue <rcb5 at msn.com>
Date: Wednesday, January 14, 1998 11:27 AM
Subject: The ear thing.


>Hey Ron,
>
>    Being one who is often unsure of my knowledge, I did some research
>and calculations on the argument that the pinna is so important in
>location of sound.
>
>    First, the articles refer to vertical sound localization. The thread
>in the group was talking about horizontal localization.
>
>    Second, one of the articles I read was actually for a lab to "prove"
>this theory is done in an anechoic chamber. I would like for them to try
>it using a stiff cardboard "barrier" with a hole in it for the pinna to
>protrude through, to eliminate the affect the body and hair have on
>sound reception. Then see if one can localize vertical sound.
>
>    I did some calculations. It turns out that the frequencies which
>seem to be most affected by the pinna are from 5,000 to 20,000 Hertz.
>Their wavelengths are about the length of the pinna and smaller. So,
>yeah, it is likely that the sound is being reflected and constructively
>and destructively interfered with close enough to the ear that one might
>be able to claim that the pinna is used to localize vertical sound. The
>offset location of the ear canal might aid in this too. But there is so
>much more to localization. Enough to make the pinna a small contributer
>to an overall picture. Maybe 5% important.
>
>    I think that this interference by the pinna is more of a filtering
>affect (I read this in the late eighties) for those frequencies.
>
>    BUT, much of my understanding about wave phenomena and sound is that
>one should be able to do with a pure tone the same demonstration as with
>noise or music. IOW the interference pattern would be more evident with
>a 15,000 Htz tone than with noise. I would then cry out loud "I was
>wrong!"
>
>    An anechoic chamber does not reproduce real world situations. This
>is an obvious statement, to be sure.
>
>    I like that one test using a cat (though not really fair due to the
>nature of a cat's ear versus a humans') where they put a small
>microphone to do an FFT analysis. But I would like to see one for a
>human ear. In fact, two or more  mic's might be needed for a 3d
>analysis, where the sound can be analyzed from different
>angles/locations around the pinna. But then the mics would interfere
>with the pinna's function.
>
>    I am writing this to you mostly to reinforce my findings in my own
>mind. I read and heard that we remember 30% of what we hear, 50% of what
>we read, and 85% of what we hear, read and see (of the same subject,
>that is). I also better remember stuff that I write about. CORE, COP and
>NDS at their best!
>
>
>Thanks,
>
>Gabe
>
>







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