 The Clarinet BBoard
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Author: krawfish3x
Date: 2003-08-12 03:26
i was doing some research online and i came across a few things about a clarinet's harmonic series, clarinets vs. flutes, different vibration patterns, etc.
here is the site: http://www.phys.unsw.edu.au/~jw/clarinetacoustics.html
my question is...(well along with many others, but just this one for now)...why does a clarinets harmonic series only use odd numbered overtones and a flute use a whole harmonic series? i know it has something to do with the open and closed cylinders, but im not exactly sure why.
also, if you goto: http://www.phys.unsw.edu.au/~jw/flutes.v.clarinets.html
there is a diagram in the middle of the page(the first diagram), can someone explain what this means?
for my sake, and any other users on this BB that come across this topic, please make it simple enough that i can understand it.
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Author: allencole
Date: 2003-08-12 04:26
I checked it out, and it gives me a headache. This is the first time that I've heard the term impedance used in acoustics. I wonder if it is a combination of resistance and reactance like it is in electronic applications.
Allen Cole
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Author: Mark Pinner
Date: 2003-08-12 06:04
Joe Wolfe, who is responsible for the above website, is a fascinating individual. He is the associate professor at Uni of New South Wales in musical accoustics and also is responsible for designing the part of the cochlear ear implant that enables deaf people to hear music. Quite an achievement. You will never get Joe to simplify anything. At some stage in the near future I am going to try to do the same harmonics test on my Oehler and Albert system horns to see if their is any tangible explanation for the perceived difference in sound ie. whether their are significant differences in the overtone series between these horns and the boehm system. Joe, however, holds one accoustical contention that many disagree with. He believes that the wood or ABS or rubber that a clarinet body is made out of plays no accoustical role at all, in other words it all happens within the pipe. This view is not widely held.
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Author: William
Date: 2003-08-12 14:21
As Spoc would say to JK, "Fasinating"
(beam me up, Scotty, clarineting is becoming too complex)
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Author: D Dow
Date: 2003-08-12 18:06
Try the Geoffrey Rendall "The Clarinet" London 1952 for an excellent description of how the harmonic series progresses from register to register!
David Dow
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Author: Matt Locker
Date: 2003-08-13 12:18
I'll try. If anyone sees any errors in this please let me know:
First & most important, air pressure in free space must be generally continuous at a point. That is, if at a point A in space you have pressure X then at some infintesimal distance A+ you must basically still have pressure X. You can't jump to some other pressure B except in a continuous fashion through space. That leads to...........
An open pipe must have the pressure (which is all a sound wave is) equal on both sides of the boundary - see above. Now, if the pipe is open on both ends, then both ends must have their ends at atmospheric pressure. If the air in the pipe is stimulated in such a way that a wave is formed in the pipe, the wave must have equal pressure nodes (atmospheric pressure) at both ends of the pipe. If you look at a standing wave, you'll see that this occurs at the full & 1/2 wavelength point - points where the pressure is always the same. An open pipe's lowest resonant wavelength is twice the length of the pipe (1/2 the frequency). Now the harmonic that is formed is going to be even divisions of that wavelength (twice the frequency) because that is the only way that the pressure nodes can still be formed at the open ends of the pipe.
A closed pipe has a pressure anti-node. Why? Because there is no interface to the outside world, hence it has the ability to take on any pressure values through the range from zero to max. The funny thing is that a pipe closed on both ends will oscillate the same as a pipe that is open on both ends. Why? Because the closed pipe has pressure anti-nodes (instead of pressure nodes) at each end - similar to the open pipes pressure nodes at each end.
Now a clarinet is a combination of closed on one end & open on the other. The closed end therefore has a pressure anti-node & the open end has a pressure node. The wavelength enclosed in that pipe is therefore 1/4 of the wavelength of that resonant frequency. In order to stimulate a harmonic you must still have that configuration. You can't just double the frequency (dividing the wavelength by 2) because that would leave you with an anti-node at the open end - not possible. However the 3rd harmonic does yield both the node & anti-node, hence the unusual harmonic characteristic of the clarinet.
Hope this helps.
Matt
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Author: BobD
Date: 2003-08-13 12:31
Very interesting. Joe Wolfe,however, is not the only one who has maintained that the material of construction makes no difference. References abound here and elsewhere. I agree with this contention, however, others maintain steadfastly that they can hear differences. It is my opinion that when they do it is because of other variables that they have not considered. No one of us knows how others perceive pain......or music.
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Author: Bennett ★2017
Date: 2003-08-13 15:31
Some helpful pages are at:
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/opecol.html#c1
which compares open/closed cylinders and closed cone
and
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/clocol.html#c1
which goes into some depth on clarinet's closed cylinder
and
http://hyperphysics.phy-astr.gsu.edu/hbase/music/clarw.html#c1
which shows spectral analysis of clarinet overtones
and
http://hyperphysics.phy-astr.gsu.edu/hbase/music/clarinet.html#c5
which explains why clarinet is closed end instrument
A good explanation - sometimes a bit technical, mostly not, is at:
http://www.physicsclassroom.com/Class/sound/u11l5d.html
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Author: Rene
Date: 2003-08-13 15:50
Matt, while your explanations are a good try, you will be asked, why a Sax does not behave like the clarinet. After all it is closed and opened too. To explain the behaviour of a cylindrical bore is a bit tougher still. I won't try, cause I might fail.
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Author: Don Poulsen
Date: 2003-08-13 16:09
The sax is different because it is conical, not cylindrical like a clarinet. (Double reeds are also conical.) By the way, I think explaining the cylindrical bore is the easiest.
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Author: Matt Locker
Date: 2003-08-13 19:46
Rene:
Don is correct of course. I'll leave it at that. For me though, the real question is, did my explanation make sense to krawfish3x in the context of the original question? I'm hoping it did.
MOO,
Matt
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Author: krawfish3x
Date: 2003-08-15 22:46
yes, the explanation did make sense and thank you for it. i dont fully understand waves and patterns of them and thats probably the problem to why i cant understand all of it.
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Author: krawfish3x
Date: 2003-08-16 00:21
now heres another question, why is it so easy for brass to use their overtone series and its hard for woodwinds?
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