 The Clarinet BBoard
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Author: krawfish3x
Date: 2003-08-10 20:48
my teacher told me that reeds vibrate in different places for each note played on the clarinet and im just curious to know where these places are. could someone in form me what they are or how i could tell?
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Author: Mark Charette
Date: 2003-08-10 21:10
krawfish3x wrote:
> my teacher told me that reeds vibrate in different places for
> each note played on the clarinet and im just curious to know
> where these places are. could someone in form me what they are
> or how i could tell?
Your teacher is right; the reed vibrates differently depending on the note. However, the vibration is pretty complex - the reed vibrates along the long axis and side to side. I've been trying to get a PhD dissertation on reed vibrational analysis online for a long time - no joy yet.
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Author: Bob A
Date: 2003-08-10 21:25
Mark said, in part:
"I've been trying to get a PhD dissertation on reed vibrational analysis online for a long time ...."
Whatever for Mark? Who would read it?
Bob A
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Author: Synonymous Botch
Date: 2003-08-11 00:03
If'n I could cipher through the sleep signs... me three.
Fascinating stuff, using fast-fourier analysis and strain gauges to capture deflections. The problem with reed measurements is dampening of the small (and rapid) excursions of the reed at nodes...
Would that best be done with high-speed photography or interferometry?
******
I think of the bee's wings description in Larry Guy's adjustment guide.
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Author: Mark Charette
Date: 2003-08-11 00:37
Synonymous Botch wrote:
> Would that best be done with high-speed photography or
> interferometry?
It was done with high speed photography, and then used to iteratively refine a a Hypermesh model, which then used FEA to approximate the stress & strain. There's 3D movies, too ...
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Author: Alseg
Date: 2003-08-11 00:47
Sounds like the famous thesis on the action of a curve ball.
I wonder if it accounted for lip pressure, speed of air, flow of air (not the same as speed) and reflective waves from the barrel, mouthpiece, and oropharynx.
On second thought...I will wait for the movie or the Cliff's notes
AS
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Author: Jerry McD.
Date: 2003-08-11 02:01
A very oversimplified explanation is that you can divide the reed into three areas that corrospond to the three registers of the clarinet (chalameau, clarion, and altissimo). The top third (the tip end) is the highest register, the middle third (especially on the sides of the 'heart') are the clarion, and the bottom third - closest to the bark- is the lowest register. I believe the reed also vibrates equally across the reed and that is why you want the reed to be balanced, more accurately you want the reed to be the same thickness on the left and the right sides of the reed from the tip all the way back to close to the bark.
This is a very rough idea of the areas where the various areas of the reed corrospond to the notes played. A good way to learn some of this is through adjusting reeds with a knife. Scrape a little in a specific spot and test to see what has changed. Do this enough and you will get a feel for how a reed works.
Mark C. - I would be interested in reading that dissertation (I think).
I hope this helps.
Jerry McD.
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Author: Mark Charette
Date: 2003-08-11 02:05
Jerry McD. wrote:
> A very oversimplified explanation is that you can divide the
> reed into three areas that corrospond to the three registers of
> the clarinet (chalameau, clarion, and altissimo).
I saw the pictures - it doesn't act this way, even with oversimplification. However, scraping in different areas is a good way to figure out generally what affects what.
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Author: Gretchen
Date: 2003-08-11 15:29
how would you even set up this research? would the reed be on a fake mouthpiece? or would there be a fake pressure (resembling the lip) on the reed? which mpc facing would you use? What size reed? seems like too many variables!
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Author: Mark Charette
Date: 2003-08-11 15:40
Gretchen wrote:
> how would you even set up this research?
A micro-camera in the mouthpiece ...
> seems like too many variables!
But you're not looking to change all the variables at once! You're just looking to see the different modes of vibration (that in fact there are, and they are of type X at different frequencies, etc.).
The questions that are answered are a subset of all the possibilities, but "you gotta start somewhere ...".
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Author: Shorthand
Date: 2003-08-11 16:20
I, too would be fascinated by this. A dissertation on this subject would probably be a great help to reed makers, esp. synthetic reed makers if they're scientifically inclined.
Just to see if I'm thinking right, Jerry is thinking what parts you adjst to effect different ranges. Mark is observing vibrations directly.
I'm betting that the parts that you adjust to effect different registers are the parts that flex the most and contribute to the spring-action of the reed. (In addtion to the standing waves in the air column.)
Therefore, the parts you adjst to effect a register may or may not move much in the pictures. A detailed FEA analysis like Marc wants to do if he ever finds the time will definitely take all of this into account, but I wanted to make it clear that a quick visual look will not tell you where the spring force is applied, only where mass is moving.
Personally, I would be fascinated to see the pictures.
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Author: Gretchen
Date: 2003-08-11 16:31
would the camera be in the way of the air stream? where would the camera go? I'm really interested in this!
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Author: CJB
Date: 2003-08-11 16:38
I'd be fascinated to see a copy of the thesis. I wrote a dissertation for my acoustics diploma about 8 years ago on what effects clarinet tone (in terms of the harmonic content). The one element that seemed to be overlooked or at best oversimplified in all the experimental papers I reviewed was the reed.
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Author: Mark Charette
Date: 2003-08-11 16:54
Shorthand wrote:
> A detailed FEA analysis like
> Marc wants to do if he ever finds the time will definitely take
> all of this into account,
Not Mark ... Don Casodonte already did much of it in his thesis
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Author: Mark Charette
Date: 2003-08-11 16:55
Gretchen wrote:
> would the camera be in the way of the air stream? where would
> the camera go? I'm really interested in this!
It's not all that complex - a small hole & fiber optic pipe in the mouthpiece. If done correctly virtually no obstruction.
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Author: Alseg
Date: 2003-08-11 17:05
How about "observing" using reflected mini Helium/Neon laser beams or even sonographic transducers?
There could be small aperatures flush-mounted on the rails and tip that record deflections over time (milliseconds or less?) without disrupting the air flow.
Quite a project!
Would love to see the thesis mentioned in the original postings.
I ordered the "Philadelphia school of clarinet" thesis over the internet. I wonder if the same repository has ALL doctoral theses available.
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Author: Mark Charette
Date: 2003-08-11 17:14
Alseg wrote:
> I ordered the "Philadelphia school of clarinet" thesis over the
> internet. I wonder if the same repository has ALL doctoral
> theses available.
http://wwwlib.umi.com/dxweb/details?doc_no=1028019
However, the thesis does not have the more "interesting" parts (movies, interactive spreadsheets, the mesh & FEA model parameters, etc.).
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Author: Alseg
Date: 2003-08-11 22:37
9612138 appears to be their catalog #
Another article that might be worth a perusal is the one mentioned in the abstract: S. C. Thompson, J. Acoust. Soc. Am. 66, 1299--1307 (1979)
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Author: Alseg
Date: 2003-08-11 22:40
Oh, and thank you Krawfish3x for bringing up this topic.
By your logon address it would appear that you are located near a very gifted woodwind tech that I know. We can hammer that out later.
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Author: krawfish3x
Date: 2003-08-12 00:34
thanks, this topic provided me with a lot of information, although a lot of it confuses me because i never really thought about reed vibrations to the extent that some of the people on the BB have. i was acctually just looking for a simple answer like "the reed vibrates from the sides in the altissimo register" so i would know if the notes didn't play in some situations i would have to tighten the corners of my mouth to lock the rails of the reed. if i knew some of that it would help for adjusting reeds too, but i guess i got more than a bargained for, haha.
i dont know the woodwind tech, Mike Hammer. nice pun. "we can hammer that out later"
Post Edited (2003-08-12 19:07)
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Author: CPW
Date: 2003-08-12 01:31
c.f Clarinet Acoustics by Gibson
Grabner's or Opperman's reed adjustment manual
Avail from Gary Van Cott which links from this website
(yeah, yeah....I do not have connections with any of the above aside from being a satisfied customer)
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