 The Clarinet BBoard
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Author: wkleung
Date: 2017-04-16 09:13
First of all, a big thank you to every single one of you who offered me advice on the matter.
I bought two 64mm barrels from a member here. The 64mm barrel raised my pitch by around 2Hz. The big factor, however, turned out to be the temperature. At the time I was complaining about my low pitch, the ambient temperature was around 13C. A week or so ago, I checked my pitch again when the temperature was around 25C. I played comfortably at around 441Hz with my 64mm DEG barrel.
I don't recall such sensitivity of pitch to temperature on other instruments I played. Is the clarinet notorious for this?
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Author: kdk
Date: 2017-04-16 17:30
Remind us - what is the instrument made of? Grenadilla? "Rosewood?" Cocobola?
I've never found grenadilla to be *that* sensitive to temperature. In any case, for any material, it warms as you play it to the point when the ambient temperature shouldn't matter that much.
I have found that the "rosewood" my Patricola C clarinet is made of is more prone to change during winter - colder *and* drier - weather. I've had keys actually bind between their pivot posts because the wood had moved (they free up when I humidify the instrument in its case).
Karl
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Author: Burt
Date: 2017-04-16 17:54
13C!! That's about 60F, awfully cold. I would think that only marching bands play at that temperature.
There are two factors which make the pitch change with temperature. The speed of sound decreases as the air gets colder, making any instrument which uses a length of pipe to determine pitch (including brass and woodwind instruments, but not bells or stringed instruments) flatter as it gets cold. The frequency (pitch) is the speed of sound divided by the wavelength. I calculated this effect as 1.6 cents per degree F, so this accounts for about 25 cents.
A MUCH smaller effect is that as the instrument gets colder, it shrinks, which would raise the pitch. When the instrument shrinks, the wavelength of the sound decreases. The size of this effect depends on the material the instrument is made of, but is a MUCH smaller effect than due to the speed of sound.
Burt
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Author: Wes
Date: 2017-04-17 00:22
Yes, wooden clarinets are very sensitive to temperature and often can take ten minutes or so of playing to come up to temperature.
I've also noted that reed condition can affect pitch. Thus, a new V12 #3 on my mouthpiece is more likely to have a slightly higher pitch to start than the same kind of reed used for hours and a little tired looking, although they both play up to pitch after warmup. The V21 and Rue Lepic reeds seem to be a bit higher in pitch to me than the V12, possibly due to narrower butts, so that is of interest to me.
Once, I played a metal clarinet in the St. Paul Winter Carnival Parade at 15 degrees F with the Minnesota National Guard Band. There actually was ice inside the clarinet after the parade and can one imagine how bad it must have sounded.
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Author: Caroline Smale
Date: 2017-04-17 01:44
I may be mistaken but I thought the major influence of temperature was on the density of the air. As it gets colder the density (mass) of the air in the bore increases so causing the pitch to lower, similar the a heavier string on a violin producing a lower tone than a thin one.
I have heard that if one drinks a lot of spirits then the alcohol in the breath reduces the density of the air and the pitch rises.
Now what a lovely way to get up to pitch.
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Author: Burt
Date: 2017-04-17 16:58
Yes, the increased density of the air at low temperature is why the velocity of sound is lower.
I've never tried sipping a cup of coffee between passages to see if that can make a difference in the pitch. Inhaling some helium might help. A metal clarinet conducts heat much better than other clarinet materials, so it may be more sensitive to ambient temperature than others.
But Caroline's approach should be more enjoyable!
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Author: Philip DeVries
Date: 2017-04-17 17:36
In winter my practice room is routinely 13C or less when I begin, and rises to about 20C once the space heater gets things warm. Pitch always is low when cold, and rises as the air temperature rises. I can't get in tune until both the air temperature is about 22C, and the instrument is warmed up. To be clear, the instrument is pretty much in tune with itself when cold, but it is the absolute pitch (according to a 440 tuner) that is flat.
I presume that the dense, thick walls of the clarinet cool the breath that is flowing through the instrument, and that is why the horn itself has to become warm before tuning is up to pitch. How long warmup takes depends on many things, including the specific heat (thermal density) of the body material, which is why plastic/rubber/wood/metal construction may make a difference.
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Author: Ed Palanker
Date: 2017-04-17 17:36
A cold clarinet is always flat and as it warms up it gets sharper. If it's a wooden clarinet one should never play it in extreme cold. When I used to tour with my orchestra in the winter I'd always open my case as soon as possible to allow my clarinets to get closer to room temperature to avoid cracking if it were very cold as well as help bring it up to pitch as I warmed up. To cold, flat, to warm, sharp. Just right, good luck, use your ears and adjust.
ESP eddiesclarinet.com
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Author: Tony F
Date: 2017-04-17 17:49
I have a wood Imperial and a hard rubber Imperial. The wood one is for indoors and the rubber one is for outdoors.
Tony F.
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Author: John Peacock
Date: 2017-04-17 18:12
Caroline, Burt: I'm afraid you're not right about the effect of density. The speed of sound in air depends very nearly just on the temperature and the typical mass of air molecules - the sound speed is closely related to the typical random speed of a molecule. We exploited this in the following trick exam question:
A violinist and a flautist play in tune at sea level at 20C. If they are now taken to the summit of Everest where the air is at the same temperature but three times lower in density, which player will be sharper?
[answer: they are still in tune]
You can change the sound speed by changing the density *only* if you achieve the density change by substituting lighter molecules. We've all heard the party trick of inhaling from a helium balloon and getting a much higher pitch. Conversely, having heavier molecules lowers the pitch: Tony Pay has written interesting things about how you are likely to be sharper after taking a fresh breath, which arises because previously the air in your lungs was full of CO2, which is more than 50% heavier than typical air molecules (this factor wins over the fact that the air you breathe in is probably cooler). And the same effect should arise with alcohol: ethanol has a similar molecular weight to CO2.
[so a more subtle answer to the Everest question is to wonder if the flute could be a little sharper after all, since the air that high might be richer in N2 as it is a slightly lighter molecule than O2. But in fact the % of O2 on Everest is the same as at sea level - only above 100km does the atmosphere become more N2 rich]
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Author: Caroline Smale
Date: 2017-04-17 21:13
John, I am not a scientist so bear with me, but aren't there two factors in play here?
The speed of sound through the air AFTER the instrument has established the basic pitch would surely delay all the wave peaks equally. So the sound might take a fraction longer to reach a listener some distance from the source, but the distance between the peaks and hence the frequency of the waves in the tone would still keep the same relationship i.e. still sound the same pitch ??
However the mechanism of the initiation of the pitch within the clarinet bore would be affected by the density of the air, and so produce a much higher pitch.
But would not the physical density of the violin string be unaffected by the air density (ignoring perhaps a small influence of lower gravity on the mass of the string) and so the basic violin pitch would remain same as at sea level ??
Did any of your captive students ever try to put this to the test ??
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Author: John Peacock
Date: 2017-04-17 22:33
Caroline: the first thing you say is right. Once the pitch (frequency) of a note is established, it's going to reach your ear at that frequency independently of what it propagates through. So what matters is only the speed of sound in the air inside the instrument. Sound waves have two attributes that describe their oscillation: the frequency and the wavelength, which are in the relation frequency = speed of sound / wavelength. But the wavelength is fixed by the size of the instrument so only the sound speed matters - which in turn only depends on the temperature of the air inside the instrument, not its density.
No, we don't have the funds to send students on fieldwork to Everest - but in effect the experiment is carried out well enough with a more modest altitude. For example, if there are any readers from Bolder, Colorado, I expect they can confirm they can get their clarinets to play at A=440 to a fraction of a semitone (say, within 1% in frequency). And yet the density of air there is 15% lower than at sea level.
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Author: Burt
Date: 2017-04-17 23:10
The Ideal Gas Law (air at room temperature and atmospheric pressure is nearly ideal) states that the density is directly proportional to the pressure and inversely proportional to the temperature (on the Kelvin scale).
The velocity of sound is proportional to the square root of the temperature and inversely proportional to the square root of the mass of the molecule in the air.
The pitch drops with increase in air density. Lowering the temperature is one way to increase the air density. Reducing the air pressure will decrease the density, but I don't know whether 1 mile of elevation has a significant effect. Mt. Everest is nearly 6 miles high.
Adding helium will decrease the density, as will blowing hot air thru the horn. Adding alcohol or a lot of carbon dioxide in the breath (both are heavier than nitrogen or oxygen) will have a (probably negligible) effect on lowering the pitch.
Caroline, I agree. A violin string will vibrate even in a vacuum; the air has little to do with the pitch of a string. Of course, you won't hear it in a vacuum.
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Author: John Peacock
Date: 2017-04-18 13:58
Burt: sorry to keep on, but some of your statements are wrong, or at least misleading.
> The pitch drops with increase in air density.
> Lowering the temperature is one way to increase the air density.
> Reducing the air pressure will decrease the density
This statement suggests that you think the pitch must rise if you reduce the pressure, thus decreasing the density of air. But to repeat, provided you achieve this reduction in pressure without altering the temperature, it will have no effect. The density can (and does) go up and down with atmospheric pressure, but we only care about the temperature - density in itself doesn't matter at all.
And even ambient temperature doesn't matter all that much. Everyone exhales air at 36C, and I presume that the air column inside a clarinet attains a temperature that is dictated more by this supply of hot air than by what's happening outside. It's easy to see that this must be the case, e.g. by considering ambient temperatures of 20C and 30C, which are easily within the range of normal playing conditions. As you rightly say elsewhere, the frequency scales as the square root of temperature in Kelvin, so that would be a frequency difference of 3/10 of a semitone. The only way way can play in tune in practice is if there is a high degree of similarity in the temperature of the air inside our instruments.
Finally, on the CO2 issue, Google tells me that exhaled air contains typically 4% CO2. CO2 weighs 1.5 times as much as the mean molecular mass of air, so that boosts the mean molecular mass by 2%, yielding a 1% reduction in the speed of sound in CO2-enriched air, i.e. 20% of a semitone. Probably any real-world effect is smaller than that, since I expect the air in our lungs always has a fair proportion of CO2, even when a fresh breath is mixed in. But even if the proportion of CO2 was (say) 4% at the end of a long phrase and 3% straight after a breath, that would shift pitch by 5% of a semitone - a detectable change.
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