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glazing whistles - acoustics

updated sat 4 sep 04


Cynthia Bracker on fri 3 sep 04

WOW! I knew I'd get to use my degree even working in the ceramic field
(My degree is in Music Education)
Musical/Acoustical aspects of glazing whistles:
1. A glazed surface is harder and more reflective than raw clay fired to
maturity, thus the whistle's TONE QUALITY will change, not the pitch (or
notes) of the whistle. My guess is that it will be "harder" sounding,
and possibly construed as louder simply because of the sharpness of the
reflection of sound. I could go into more acoustical detail here if
anyone is interested in hearing about the 3 parts of a sound and
overtones and such.
2. Some people have already mentioned keeping glaze out of the "throat"
of the whistle. I don't think that's absolutely necessary if you are
carefully with your glazing. The reason that glazing this area might
cause a loss of sound is that it could possibly cause a roundness to
that edge. The sound in a whistle is produced via "edgetone vibration"
This means that as a column of air strikes against an EDGE it will begin
to alternate over and under the edge, thus producing the sound.
(Someone referred to this as the "reed" part which is a good analogy.
Reed vibration is another form of sound production) The important thing
is that the edge be sharp. It can be glazed, just make sure to make it
a thin coat of glaze. After the firing, if it does not make a sound,
you can try "sharpening" the edge with a file. Of course leaving it
unglazed is also fine.
3. You do want to make sure that any finger holes stay free of glaze
drips (ok to glaze edges, as long as you don't have a "bubble" partially
covering the hole. This will change the pitch of the instrument.
(Also, a whistle with tuned holes is technically an Ocarina, not a whistle.)

Just so you all know, I have cc'ed this to one of my former music ed
professors. I'm a little rusty on my Acoustics, so if I've gotten
anything wrong, I'm sure he'd jump at the chance to mark up my e-mail
with an imaginary red pen. I promise to send a correction if he does.

Cindy Bracker

BobWicks@AOL.COM on fri 3 sep 04

Hi Cindy:
I saw your letter in Clay Art and was interested as I am currently doing
research on the acoustics for the Ocarina. You are absolutely right about a
glazed surface on the Ocarina. It will definitely change the tonal quality to a
much harsher none. I use terra Sigillata and the tonal quality is a nice
soft mellow tone. Since TS does not run, it is a most compatible decoration
media to work with the ocarina. This media also is great for sgraffito
decoration. The only glaze that I use is on the part you put in your mouth and
sometimes in small areas for artistic effect with overglaze. For the most part
people think the Ocarina is a very simple instrument, but there is much more
to it than what meets the eye.

My research deals with tuning and how it can be controlled by the craftsman.
I currently have a method whereby you can change the Fundamental Key of an
Ocarina by as much as four keys. This makes it possible to tune the ocarina
to an instrument that you are accompanying with.

You are right on track regarding glaze on the flute or any wind instrument.
Keep up the good work.

Good luck'
Robert B. Wicks, Prof. Emeritus, Art & Photography
Harrisburg Area Community College