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
>>
