Hi Riley:
I've seen that web site you mentioned, and actually exchanged several
emails with Joe Wolfe.
In fact, I would have to be honest and say that Joe and colleagues' work is
what got me
stimulated in this direction in the first place.
What they have done is measure the acoustic impedance of the bore X(f).
What they do is stimulate the bore artificially and measure the what is
called the linear response function
or bore impedance.
What we are talking about (that hasn't been done to my knowledge) is
measuring the I(f), the input spectrum from a trained player blowing the edge.
The sound spectrum S(f) that you make and hear when you play (such as you
might see in crude from in a
spectral analyzer like the ones that are on tuner programs for your pc) is
the product of these S(f) = I(f)X(f).
Translated, and what you already know, what you get out is the result of
what you put in and what the bore
then does to it. The player controls the input spectrum through the
embouchure. Good arguments and some basic physics
as well as some simple experiments (see Nelson's page on the utaguchi)
indicate that this
input spectrum is very broad band, without sharp peaks, in other words
noise, chaos. If you listen
to it without the bore it will sound like static. This fits with the physics
of what happens at an edge when it break into what is essentially
turbulence. This turbulence powers the bore.
There has be a back and forth debate between some of us about how much the
input spectrum is controlled
by the embouchure. This would bear on the question of what the player is
doing (and possibly *can* do) to
alter the sound coming from the instrument. One hypothesis is that the
output spectrum is broadly humped
and all that the player can do is move the hump position, but not have
control of the shape. This would be enough
to explain, by the way, bending notes and switching octaves. But the other
hypothesis is that a good player
might be able to control this much more. Different players might do
different things as well, and of course some of this
difference might be a response to the particular instrument they are playing.
Anyway, I was planning on using what they learned about measuring spectra
from various woodwinds to build
the detectors, and possibly talking again to Joe about how to do it. Since
my profession interests lie elsewhere, and this
is just for fun, I might skimp on the cost and sophistication of the
equipment to what I can cannibalize from radio shack.
But rest assured this is all built on what Joe and company have done.
Marko
At 07:35 PM 9/16/2003 +1000, you wrote:
>Hello all.
>
>Apropos the acoustic impedances discussion, especially the last one from
>Mark re: the imput spectrum, the following website might be of interest.
>
>Briefly, it's been done...
>
>http://www.phys.unsw.edu.au/~jw/shakuhachiresults.html
>
>
>Best regards, Riley
>
>
>Dr. Riley Lee
>PO Box 939
>Manly 1655 NSW Australia
>Tel: +61 (0)2 9976 6904
>Fax: +61 (0)2 9976 6905
>mobile: +61 (0)414 626 453
>www.rileylee.net
>
>List subscription information is at:
>http://communication.ucsd.edu/shaku/listsub.html
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