Vibrating Chanters

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Vibrating Chanters

Postby Barry Say » Wed Feb 22, 2012 10:07 am

In a discussion elsewhere, a well-known piper said:
The slim design of the chanter means I can also feel the wood vibrating under my fingertips, and I'm sure this must contribute to the overall sound of the pipes.

I have experienced this phenomenon, but my physics head says that if the wood of the chanter vibrated it would be withdrawing so much energy from the wave in the bore that the chanter would hardly sound. I believe that players can feel the vibration in the air in the column of air under the fingers.

Any thoughts? Is John Gibbons reading this?

Barry
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Re: Vibrating Chanters

Postby Francis Wood » Thu Feb 23, 2012 10:07 am

This is an entirely simple case of 'for wood, read air'. There can be little doubt that the wood does vibrate to some extent, but the vibration caused by the acoustic energy passing through the air in the bore will be vastly more evident. Since the fingers supporting the chanter are almost all placed on holes, who can honestly insist that what they are detecting is the vibration in the solid material, rather than the energy in the gas?

The 'slim design' is likely to make this more evident because the fingers are necessarily closer to the bore without the interfering 'chimney' effect of a tone hole through a thicker wall. 'Slim design' chanters are also likely to be Reid-based, with the characteristic large tone holes.

That tingling beneath the fingers is a useful and reassuring sign that the reed and bore are working very well together. I was recently very puzzled by this, since the chanter felt extremely healthy, yet didn't sound sufficiently bright or responsive. I tried a number of remedies, all of which produced no benefit.

The eventual solution was wonderfully effective and is one I've never seen recommended in any piping forum. I went and had my ears syringed.

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Re: Vibrating Chanters

Postby John Gibbons » Thu Feb 23, 2012 11:49 pm

Seems I never posted my reply to this. On instruments with bigger bodies, eg recorders, Border pipes, body resonance has a significant effect on the pitch. So it matters a lot what wood they are made of. NSP have higher pitched body vibration modes, being smaller, but are still of similar pitch to a tenor recorder. The harmonics though may couple strongly to the body vibrations. I doubt if that would have a huge effect on the pitch, but would affect the 'colour' a bit. Maybe this is why nearby notes have drastically different tone colours.
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Re: Vibrating Chanters

Postby Barry Say » Fri Feb 24, 2012 9:19 am

John Gibbons wrote: Maybe this is why nearby notes have drastically different tone colours.


From personal experience I have found that the particular properties of the chanter reed can lead to individual notes having tone colours markedly different to the rest of the chanter. A small scrape has cured the problem. I don't suggest that this is the whole answer, rather another variable to throw in the pot.

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Re: Vibrating Chanters

Postby John Gibbons » Fri Feb 24, 2012 8:14 pm

I see that variation in colour as a feature, rather than a bug, so long as no note sounds nasty, of course.
The ideal that every note sounds the same except for pitch is best achieved with electronic rather than real musical instruments.

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Re: Vibrating Chanters

Postby John Gibbons » Sat Feb 25, 2012 12:36 pm

It is also worth noting that unless the pitch of the note is in tune with a body resonance,
the vibrational modes of the body will hardly be excited.

With the wood being a thousand times denser than air, nearly all the energy will be reflected at the boundary.
Only in the resonant case will you get significant coupling to the body modes.
So it won't dull the sound significantly.
Much less than the coupling to the outside air through the open hole, I'd guess.

There's a musical instrument acoustics group at Sydney U does a lot on body resonances.
It must be a fun research topic.

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Re: Vibrating Chanters

Postby Ben Power » Mon Feb 27, 2012 10:17 pm

I'm inclined to agree about the holes and air being what one feels—the same is true of wooden flutes, though with bigger holes. They also seem to do it more after being played for some time (when the bore is wholly sealed with moisture?). somewhat tangentally, I was once visiting Desi Seery, the Uilleann pipemaker up in Greystones, South of Dublin. Desi is a great believer in not wood, being one of the first to consistently turn out Irish instruments in Delrin, some of which were (and are I suppose, as they're more or less indestructible) very good. He used to take an old broken centre joint of a wrecked wooden flute and smash it to smivs on his bench vice, and then take the centre joint of one of his delrin models, bash the vice with it, throw it on the ground and dance a step on it, and then pick it up, put a flute together with it and play a tune, to make his point. Anyway, while I was there, I noticed a silver chanter on the wall, and upon asking about it was told it was stainless steel. Apparently someone had told him "it couldn't be done" and he'd taken it personally. He said it played fine, but didn't sound very good. Now one of them would have to be pretty reflective of vibration I'd have thought, and not at all absorbent of sound waves. Nor do wooden flutes tend to sound the same as the metal ones. Perhaps the vibrational absorbance of the wood is precisely one of the characteristics that speaks to the tone and, as such, we'd be able to feel it? Still much less than the air on the fingers though I'd have thought. What about on the right thumb? Do you feel it there?
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Re: Vibrating Chanters

Postby adrian » Mon Feb 27, 2012 11:51 pm

I have this marvellous experience, were everything comes together and the chanter resonates.
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Re: Vibrating Chanters

Postby John Gibbons » Mon Feb 27, 2012 11:54 pm

Acousticians seem to be pretty convinced there is no significant effect of body material on either pitch or tone colour.
Most effects that are observed are ascribed rather to the different dimensions of the 'same' instrument when made in different materials.
But I think I saw a paper once on how resonances of the body can - if in tune - couple to resonances of the air column.
Anyone who makes Border pipes will tell you that hole spacings have to be slightly different if the chanter is made of a different wood;
but why is this? Are all the dimensions of the chanters otherwise identical? If so, I would blame body resonances coupling to the cavity resonances. But generally it seems to be a small effect.

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Re: Vibrating Chanters

Postby Francis Wood » Tue Feb 28, 2012 12:09 am

Acousticians are probably right about the effect being acoustically small. Musicians are also probably right about the detectable musical difference offered by a preferred body material. The same general principles apply to cheese.

The cheapest bit of processed cheese is probably (more or less) chemically close to the best farmhouse produced and appropriately aged gourmet item. It's the small differences that are the important ones. In instrument making everything matters and everything is a variable. A certain quantity of superstition also assists the mix, I believe.

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