 The Clarinet BBoard
|
Author: davidsampson
Date: 2008-06-11 01:14
Ok I have several questions related to the acoustics of clarinets, and instruments in general.
1) What is the formula for the frequency of a note played by a clarinet? Not like, what is the frequency of C below the staff, I can calculate that. But given the length of the tube and the size of the tone holes, how do you calculate the pitch that will be played? How does it change for a polycylindrical bore?
2) How does the shape of the mouthpiece and barrel affect the pitch?
3) Given a tube of a certain length, how do you determine where to place tone holes, and what size they should be?
4) This one is a little different. Why can't bass clarinets be built as large clarinets? What about them requires two register holes (at least)? Also, why are the key mechanisms so much more complicated? Shouldn't they be essentially just larger clarinets? Why do basses utilize a half-hole for the 5th harmonic and higher, whereas clarinets use open-holes?
Feel free to answer in as complicated a manner as need be, I am taking calculus and college level physics. Thanks in advance.
|
|
Reply To Message
|
|
Author: Ryder
Date: 2008-06-11 01:29
Try here-
http://www.phys.unsw.edu.au/jw/clarinetacoustics.html
I'd seen it a long time ago, but it was way over my head. Mabey you will have better luck. It seems to be fairly detailed.
Mabey you can explain to us what exactly a reverse taper barrel does.?.?.?
|
|
Reply To Message
|
|
Author: Ed Palanker
Date: 2008-06-11 02:11
I’ll take an uncomplicated shot at the bass clarinet part but I can’t get into tech reasons because I don’t understand that stuff. I have trouble figuring out how to work my cell phone. I think a bass clarinet can be built as a large clarinet but you would have to sit on a stool to play it so it needs the bent neck to make it accessible. A wooden bell works fine and some after market people do make them. I think the reason for the more complicated key mechanism is because they have covered holes since it’s too large to cover them otherwise. That leads to having more keys to depress so you can cover all the holes with a normal finger reach. Then there’s the register keys. The student bass clarinet only has a single register key so it doesn’t need all the mechanisms to work the double automatic register keys. The old models that were not automatic had less key work but you had to slide from one register key to the other. The students models with only one register key do not voice the upper register very well so it may be less complicated but don’t play very well in the clarion register. I can only surmise that the reason for needing the second register key, and the use of the half hole as sort of a third register key, is needed because of the length of the instrument to voice those registers correctly. Probably has something to do with the larger bore too. Not a very technical explanation. The last reason for the complicated key work is the extension down to low C requiring all those long rods and keys. I guess that’s somewhat of an explanation. Maybe not what you wanted but that’s all I can offer as a player. Now I'm going to try to figure out how to turn my cell phone on, sorry. ESP www.Peabody,jhu.edu/457 (Listen to a little Mozart)
|
|
Reply To Message
|
|
Author: rtmyth
Date: 2008-06-11 13:46
Good web site above. Also, study "Fundamentals of Musical Acoustics", by Benade. "Vibration and Sound", by Morse, "Theory of Sound", by Rayleigh, "Science and Music", by James Jeans, "Music, Physics and Engineering" , by Olson. Let me know if you need more after you have finished these. There is also an excellent Shaum Guide to Acoustics which may be helpful in ploughing through the above. When the science is exhausted, the experience and talent of folks, such as Ridenour, Backun, etc, come into play.
richard smith
|
|
Reply To Message
|
|
Author: William
Date: 2008-06-11 14:10
And even after all of the math and research is done, accousticians still can't design the perfect concert hall nor figure out why a Stradivarius violin sounds the way it does. Good luck with clarinets...............
|
|
Reply To Message
|
|
Author: Alseg
Date: 2008-06-11 14:36
Look up Helmholz equations.
Former creator of CUSTOM CLARINET TUNING BARRELS by DR. ALLAN SEGAL
-Where the Sound Matters Most(tm)-
|
|
Reply To Message
|
|
Author: David Spiegelthal ★2017
Date: 2008-06-11 14:40
As far as register vents go, technically every note should have its own unique vent for the second register, as the purpose of the vent is to cause the standing wave inside the instrument to subdivide and, because each note of course has its own wavelength, the length of the corresponding upper 12th also has a unique wavelength whose generation the register vent is supposed to facilitate. It happens that a vent that is approximately correct in size and location is adequate to 'trip' the standing wave into subdividing and going up the 12th in most cases; especially with smaller clarinets (as well as saxes and oboes, by the way); but the larger the instrument, the greater the number of 'dedicated' register vents are needed to really obtain adequate response and intonation in the second register.
Bass clarinets (as well as most saxes and oboes) generally need at least two register vents to perform well; larger clarinets (contra-alto and contrabass) and baritone and bass saxes really need three(!) to perform well in the upper register. At ClarinetFest in 2006 at the University of Maryland, the gentleman playing a beautiful Henri Selmer rosewood BBb contrabass clarinet with the British Clarinet Choir (I may have their name wrong, apologies) had added TWO additional vents to his instrument for a total of four! And he could play easily in the upper clarion and altissimo, like nobody I've ever heard before or since.
This is not much of a technical explanation, but I hope it helps a bit.
|
|
Reply To Message
|
|
Author: Don Berger
Date: 2008-06-11 15:30
Very well said, Fellas, that should keep DSampson busy for a bit, and perhaps most of us to try to recall our studies in physics and calc, diff eq., transfer functions etc, of our youth !! Don
Thanx, Mark, Don
|
|
Reply To Message
|
|
Author: Bob Phillips
Date: 2008-06-11 15:54
David Spiegelthal is spot on (as usual and expected).
Think of a stringed instrument. A string is fastened at the top of the finger board and at the bridge. Instead of bowing, pluck the string. It vibrates making a blur that's sort of football shaped --with the maximum width midway along the string. To get the string to vibrate an octave higher, the player touches the string at mid-point --sort of a register key.
The air column in a clarinet is similar, but effectively twice as long as the clarinet (the closing of the reed against the mouthpiece reflects a pressure wave back down the tube, while an oble reflects a "vacuum" wave). So, to get the clarinet to produce its next harmonic, we need to "touch" the vibrating medium at the 1/3 point along its length.
So, long E up a 12th to long B calls for the register key vent to be drilled in the clarinet about 1/3 of the way down the tube from the mouthpiece to the flare of the bell.
OK, so we poked a hole in the horn to force it to blow the 3rd harmonic of long B. What happens when we want to overblow, say pinch E to get clarion B? Well, we go up the horn closer to the mouthpiece and drill another register vent. And repeat the drilling for each pair of 12ths.
This is a tough job because we don't really know where the upper end of the air column really is -probably somewhere close to the beak of the mouthpiece --but (no doubt a bit down the reed toward the bottom of the mouthpiece window). So, there were probably a lot of holes drilled and filled with wax in the development of the first clarinets.
On Bb clarinet a single register vent hole works pretty well. Makers have that hole location pretty dialed in --its within a couple millimeters of being the same for all instruments.
But when the air column is longer --as it is on a bass clarinet (twice as long), the distance between the optimal locations for the many "needed" register vents just physically gets longer, and the compromise needed to find a single vent that plays well for all notes in the fingering sequence is too great, and it is necessary to drill more holes in the instrument and figure out how and where to switch from one vent to the next.
On polycylindrical bores. You need to check me on this: The bore is stepped up in diameter to compensate for the effect of a tone hole. Like the register key location, the number and location of bore diameter steps is a matter of compromise and judgment.
Bob Phillips
|
|
Reply To Message
|
|
Author: timg
Date: 2008-06-11 16:07
The essential principles are quite well explained on the Hyperphysics website. See for example these pages:
http://hyperphysics.phy-astr.gsu.edu/hbase/waves/opecol.html
and
http://hyperphysics.phy-astr.gsu.edu/hbase/music/clarinet.html
However this does not tell you enough to design a real clarinet. In practice you need to take into account a lot of details, such as the variation in the speed of sound with frequency and bore shape, the inertia of the air in the tone holes, and friction in the air flow.
The clarinet isn't really a closed pipe, and there are important external factors including embouchure, reed quality, air support and mouthpiece design These would need to be measured and quantified in a precise way. You'd also need to choose which compromises you are prepared to make: improving one note will have an adverse effect on another.
Reducing all this to equations which tell you how to build the perfect clarinet is simply not possible. A better approach would be to make a numerical simulation of a lot of different hypothetical designs and progressively optimise the design that way. Making such a simulation accurate would be quite a task.
-Tim
|
|
Reply To Message
|
|
Author: LesterV
Date: 2008-06-11 22:56
Another important factor affecting sound speed is the chemical composition of exhaled breath. It differs from air in that, when you are at rest, it is approximately 4 percent carbon dioxide while only 16 percent oxygen and varies while you play. The carbon dioxide lowers the sound speed causing a flatter note than would atmospheric air. Fortunately the higher temperature of your breath partially compensates for the excess carbon dioxide.
One way to demonstrate this is to increase the carbon dioxide content even further by going up and down a flight of stairs many times immediately before playing. Then sit and try to play a note while checking your tuning. The first few seconds after each breath will be normal as it is air from the windpipe rather than from your lungs. Then you will go flat, very flat. It will also be difficult to hold a note very long as excess carbon dioxide building up in your lungs is what makes you feel you need to take another breath.
|
|
Reply To Message
|
|
Author: nahoj
Date: 2008-06-14 11:06
Another good book (I just started it): "Acoustical aspects of woodwind instruments" by C.J. Nederveen, published at Northern Illinois University Press. Lot of mathematics.
|
|
Reply To Message
|
|
Author: rgames
Date: 2008-06-16 03:14
I've not been through all the references mentioned here but one aspect of musical acoustics that always seems to get neglected (mainly because most people who write about it are not musicians) is this:
the resonant volume of the instrument includes the oral and nasal cavities. It does not stop at the mouthpiece.
That's why you can play the gliss in Rhapsody in Blue. Most clarinetists can finged a C above the staff and, without moving any fingers, play any note between that C and the one below it. Physically, you are changing the length of the resonant volume by enlarging your oral cavity. So, you're basically making a "longer" instrument.
Because the differences in frequency are smaller for higher notes, it's easier to change the pitch of high notes. You have a fixed amount of volume to work with (determined by phyisiology) and it happens to be well suited to the upper range of the clarinet; you can't really enlarge your oral cavity enough to significantly alter the wavelengths of the lower register.
So, there's one example of 12 notes within one octave from a single fingering. Many "physical" explanations seem to overlook that point. It also explains why people can play out of tune. If the pitch were only a function of the instrument, everyone woule play the same exact pitch when using the same fingering!
rgames
____________________________
Richard G. Ames
Composer - Arranger - Producer
www.rgamesmusic.com
|
|
Reply To Message
|
|
Author: vjoet
Date: 2008-06-16 15:21
Hi,
In the book *The Art of Clarinetistry" by William Stubbins are the specifications of where the tone holes need to be placed and the size of them -- page 180, 181 Tone Hole Diameter and Placement.
This will give you a general idea, but I'm sure the polycylindrical bores of modern clarinets complicate this considerably.
Vann Joe
(amateur)
|
|
Reply To Message
|
|
Author: Bassie
Date: 2008-06-16 15:44
> increase the carbon dioxide content ... Then you will go flat, very flat.
Is this real? Is this yet another reason why we go flat when we're getting tired and / or nervous?
|
|
Reply To Message
|
|
Author: Tony Pay ★2017
Date: 2008-06-16 16:00
Bassie wrote:
>>
> increase the carbon dioxide content ... Then you will go flat, very flat.
Is this real? Is this yet another reason why we go flat when we're getting tired and / or nervous?>>
Don't know about that -- but the effect of CO2 or He is real; see:
http://www.woodwind.org/clarinet/Misc/breatpit.pdf
Tony
|
|
Reply To Message
|
|
Author: Bassie
Date: 2008-06-23 09:18
So I've been experimenting with this and I'm beginning to think it might actually be true. If I play a long passage without breathing, with concert-night nerves... I feel I'm going flat; I start to have to pinch the notes up, and eventually squeaks appear. If I remember to breathe properly it's a heck of a lot easier - just through breath discipline. In fact, the first entry after a really deep breath begins to sound sharp. Honestly I reckon there must be truth in this, above and beyond any psychology (or hyperventilation :D )
|
|
Reply To Message
|
|
Author: MichaelR
Date: 2008-06-23 13:42
Tony Pay wrote:
> Don't know about that -- but the effect of CO2 or He is real; see:
>
> http://www.woodwind.org/clarinet/Misc/breatpit.pdf
Did you happen to study tone shift in asthmatic players before and after use of an inhaler? Use of Abuterol increases oxygen absorption.
--
Michael of Portland, OR
Be Appropriate and Follow Your Curiosity
|
|
Reply To Message
|
|
Author: skygardener
Date: 2008-06-23 14:05
Often, if I have an exposed passage on 'A' in the low register, I will take many many breaths to keep the pitch as high as I can (the low register of my A is very flat).
|
|
Reply To Message
|
|
Author: Gordon (NZ)
Date: 2008-06-23 16:19
"3) Given a tube of a certain length, how do you determine where to place tone holes, and what size they should be?"
Have you considered that it is way more complicated than. Every tone hole represents a messed up bore (no longer a perfect cylinder), that affects every tone hole placement further down the instrument.
And always, there are choices, such as a smaller tone hole, further up the instrument, producing the same pitch, as is the forced case for C#/G#, in order to make enough space for the centre tenon.
And the length of the tone hole chimneys also affects pitch.
As does undercutting of the tone holes. This may be of interest:
http://www.clarkwfobes.com/Tuning%20article/Tuning%20the%20Clarinet%20for%20PS.htm
If you get hold of some of the books on acoustics of the clarinet, eg Benade's one mentioned in an earlier post, you will quickly get into this sort of complexity:
http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=JASMAN0000750000S1000S17000004&idtype=cvips&gifs=yes
Is that what you are looking for? If so, get some appropriate text books, as listed earlier. :-)
Interesting statement: http://www.speech.kth.se/smac03/abs05_link.html
One of Fletcher's books:
http://books.google.co.nz/books?id=9CRSRYQlRLkC&pg=PA487&lpg=PA487&dq=clarinet+tone+holes+lattice&source=web&ots=RobfeG6fhm&sig=mk4TM38P0UYvtdpncnw4bIX6JpQ&hl=en&sa=X&oi=book_result&resnum=5&ct=result
Post Edited (2008-06-25 04:40)
|
|
Reply To Message
|
|
Author: Paul Aviles
Date: 2008-06-24 03:59
Dear Bassie,
You've never burped while playing? Boy, talk about lowering a note!!!
...............Paul Aviles
|
|
Reply To Message
|
|
The Clarinet Pages
|
 |
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
.jpg){kind=small}
