Hi,
Derek Pierce wrote:

> I  remember reading that the vertical placement of sound is recognised by the
> effect that the ears shape has on it .Sound reaching us from variuos heights is
> filtered by the ear to a different degree depending on its height.
> Derek Pierce

The skin of the ear acts as a bandpass filter. Since it is asymmetrical
about each axis, clues are gained about where the sound is coming from,
(up, down, in front, behind). I have heard this demonstrated by
synthesising a shallow bandpass filter, (about 3dB I think) and sweeping
it up and down over a noise source. The reason the bleeper idea wouldn't
work I suspect is that there was an insufficient number of frequencies
in the source. Incidentally you must close off one ear, (stick your
finger in it) to hear the effect. No, it's not a joke- you really hear

Hmm... this might be something..
The problem is to find the right parameters for the BP-Filter.

My first experiment was to simulate the first ground-reflection,
but it didn't work. (That's why the question about how the sound
reflects)

Does anyone have any data's regarding on how the head act as a filter?
(rolloff etc)

.--- -- -  -
| Anders "Pipe/Nature" Andersson, pipe@algonet.se
:



>> I  remember reading that the vertical placement of sound is recognised by
>the
>> effect that the ears shape has on it .Sound reaching us from variuos
heights
>is
>> filtered by the ear to a different degree depending on its height.
>> Derek Pierce

>The skin of the ear acts as a bandpass filter. Since it is asymmetrical
>about each axis, clues are gained about where the sound is coming from,
>(up, down, in front, behind). I have heard this demonstrated by
>synthesising a shallow bandpass filter, (about 3dB I think) and sweeping
>it up and down over a noise source. The reason the bleeper idea wouldn't
>work I suspect is that there was an insufficient number of frequencies
>in the source. Incidentally you must close off one ear, (stick your
>finger in it) to hear the effect. No, it's not a joke- you really hear
>the sound seem to go up and down. It also works on headphones.

Do a net search on Head Related Transfer Functions or HRTF's. You should
get more than enough to keep you busy for a while.

At 1:43 PM +0100 10/4/98, Anders Andersson wrote:
>Does anyone have any data's regarding on how the head act as a filter?
>(rolloff etc)

-------------------------------------------------------------------------------
Erik Spjut (pronounce ju as long u or yew) - Associate Professor of Engineering
and  Associate Director for Engineering Computing,  Center for Design Education
Harvey Mudd College, Claremont, CA 91711-5990  USA
Erik_Spjut@hmc.edu      Ph & Voice mail (909) 607-3890      Fax (909) 621-8967

Anders Andersson wrote:
> Does anyone have any data's regarding on how the head act as a filter?
> (rolloff etc)

Does your version of Csound have the "hrtfer" opcode?

        aLeft, aRight   hrtfer  asig, kAz, kElev, "HRTFcompact"

("HRTF" stands for "head-related transfer function".)

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