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 Stopped pipe - is there an explanation?
Author: Plonk 
Date:   2019-02-12 01:32

I'm reading David Pino's book "The Clarinet and Clarinet Playing" (which is excellent ). My edition is 1998. I'm reading about the cylindrical bore and that the clarinet acts as though it's a stopped cylindrical pipe when in fact... the bore is not cylindrical and it's not a stopped pipe, which Pino shrugs off with "a full explanation has yet to appear"....

Is this still the case? Are the clarinet''s acoustics still a mystery or is there an explanation (hopefully one which a not very scientific person can understand?!)

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 Re: Stopped pipe - is there an explanation?
Author: Paul Aviles 
Date:   2019-02-12 02:57

Not a mystery, but there is physics involved. Another example of a stopped cylinder is an organ pipe. I assume that when Pino says the clarinet is not a cylinder, he is referring to the "details" of it being polycylindrical. It is worth noting that the wave form folds back on itself, making the clarinet sound as if it is about a foot and a half longer than it really is.




................Paul Aviles

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 Re: Stopped pipe - is there an explanation?
Author: Caroline Smale 
Date:   2019-02-12 03:38

The clarinet acts as a stopped pipe because the reed effectively closes one end of the tube.
As opposed to a flute where the blow hole is open all the time.

The bore does not have to be "exactly" 100% parallel to performas a cyclindrical bore.

Try Arthur Benades book on musical acoustics for a full explanation or there are many other online resources too.



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 Re: Stopped pipe - is there an explanation?
Author: Bennett 2017
Date:   2019-02-12 03:44

This site has a pretty clear explanation of stopped and open pipes (and why the clarinet produces mostly odd harmonics (3, 5, etc).

https://www.khanacademy.org/science/ap-physics-1/ap-mechanical-waves-and-sound/introduction-to-sound-waves-ap/v/standing-waves-in-tubes-part-1



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 Re: Stopped pipe - is there an explanation?
Author: derf5585 
Date:   2019-02-12 05:23

"The clarinet acts as a stopped pipe because the reed effectively closes one end of the tube"

Oboes are stopped pipe also. But overblow the octave.

fsbsde@yahoo.com

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 Re: Stopped pipe - is there an explanation?
Author: Paul Aviles 
Date:   2019-02-12 07:00

Oboes are not cylinders, they are conical bore instruments.





...................Paul Aviles



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 Re: Stopped pipe - is there an explanation?
Author: Luuk 2017
Date:   2019-02-12 15:16

The clarinet acts by good approximation as a one-side stopped cylindrical pipe, with small deviations from that.

You could say it's acoustical behavior is for 95% like a pure one side closed cylindrical pipe, and for 5% deviates from that model. May be 80-20 or 99-1, but the message is: think one side closed pipe and you understand all major behavior. Example: why is the lowest note of a Bb clarinet 146 Hz, while the lowest note on the oboe (almost the same length) is 233 Hz?

Of course, the details (like: what are the pros and cons of French vs. German bore dimensions?) may be more or less subtle and complex, and are responsible for the majority of subjects and discussions on this board. To get a hint of the details, start with Benade.

'A full explanation' may never appear because a mathematical model covering 100% of the details will be impossible to draw up, and impossible to solve.

By the way, a clarinet does not sound as 'if it is about a foot and a half longer than it really is': it sounds as what it is. A pipe, closed at one side, with small deviations.

Regards,

Luuk
Philips Symphonic Band
The Netherlands

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 Re: Stopped pipe - is there an explanation?
Author: Paul Aviles 
Date:   2019-02-13 04:42

HA! Touche.


But you did mention the 146 vs. 233 Hz disparity.



...............thanks,




.....................Paul



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 Re: Stopped pipe - is there an explanation?
Author: Plonk 
Date:   2019-02-15 17:52

Interesting, thanks!
So if you stop a pipe with a reed, at what point does cylindrical become conical? I ask because the flute is clearly cylindrical, but the clarinet is clearly wider at the end of the bottom joint than it is at the top of the upper joint, so it's "a bit" conical but still behaves like a cylinder. How much of a flare is needed to make a change in the way the waves behave, or in other words when does a clarinet turn into a sax?

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 Re: Stopped pipe - is there an explanation?
Author: Burt 
Date:   2019-02-15 18:33

The clarinet APPROXIMATES a stopped pipe with a sound wavelength APPROXIMATELY 4 times the physical length. It's not quite cylindrical, the holes are not big enough to accurately approximate the open end, and the mouthpiece tip is not quite closed. One source I read said that there is a very small amount of energy in the even harmonics, presumably because the approximation is not perfect, but I have not measured it.

At very high frequencies (short wavelengths) where the quarter-wavelength approaches the diameter of the bore, the approximation is not nearly so good. No clarinet fundamental tones are nearly that high, but overtones are.

Could the mouthpiece tip opening be a small factor in how good the stopped pipe approximation is? Should an open tip play flatter, or does the player squeeze the reed more with an open tip mouthpiece to produce the same size opening?



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 Re: Stopped pipe - is there an explanation?
Author: derf5585 
Date:   2019-02-16 00:53

Very technical

Clarinet acoustics: an introduction
https://newt.phys.unsw.edu.au/jw/clarinetacoustics.html#pipe

fsbsde@yahoo.com

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 Re: Stopped pipe - is there an explanation?
Author: Fuzzy 
Date:   2019-02-16 09:08

Plonk,

You might also find this thread from 8/2018 interesting. The focus is slightly different than your question, but the underlying principles/understanding covers a lot of things to think about in the same vein. It opened up some new concepts for me.

http://test.woodwind.org/clarinet/BBoard/read.html?f=1&i=468004&t=467926

Fuzzy

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