WTT: What's the effect of wall thickness?

[Jerry Freeman]

The O'Riorden thread, and especially the comment about their heft, has me wondering. What's the effect (particularly in a wooden whistle) of thicker or thinner walls on the behavior, timbre, etc. of the whistle?

I'm not just asking out of curiosity. The more info you folks provide, the more I can come up with new, improved (and hopefully affordable) whistles for y'all. I'm working on some ideas with wood. If I can get the result I'm looking for, it could be very cool.

Best wishes, and thanks for your kind help,
Jerry

[chas]

The only obvious thing is, the holes have to be bigger because there's more resistance to the air getting up out of the shaft.

My only heavy-walled woods are Wilson and Bleazey (. These whistles both have big sounds; I dunno if that's the heavy walls or not. The classic heavy-walled plastic whistles are the Water Weasel Bb and A, both of which are big-sounding whistles that sound more like low whistles. The wooden Weasel Bb that I have doesn't have nearly as authoritative sound as the plastic. It has much thinner walls than the PVC.

[raindog1970]

I think this is a good question that Jerry has asked, and I too am curious about it.
My experience has taught me that volume mostly comes from the voicing of the whistle... but I'm still a newbie, and have much left to learn about whistle making.
To be more specific though, a long, thin blade with a sharp edge will prodoce a louder whistle than a short, thick blade with a blunt edge.
The size of the window also plays a big part in determining volume... a larger window will produce a louder whistle than a smaller window.
The wall thickness of the tube certainly plays a part in hole size and placement, but I don't believe that thick-walled tubes necessarily require large holes... it's all a matter of placement that determines the necessary hole size.
Tonal characteristics, on the other hand, are greatly affected by the wall thickness of the tube, and by the material it is made of.
The same head on different tubes made from variuous materials will produce a different tone... sometimes the difference is subtle, and sometimes the difference is very noticeable.
If anyone with more knowledge on the subject would be so kind as to share it with us, it would be greatly appreciated.

[Hiro Ringo]

John Sindt once answered to me that he suspected the thickness affected the sound much more than materials. That's the way he thinks so he uses the material which is the most easily available(This part is what I personally think).

I somehow feel happy when sombody is doing something creative.

[chas]

My experience has taught me that volume mostly comes from the voicing of the whistle... but I'm still a newbie, and have much left to learn about whistle making.
Tonal characteristics, on the other hand, are greatly affected by the wall thickness of the tube, and by the material it is made of.

I wish we had more/better adjectives. By "big sound" I don't mean volume (in which case I'd say louder), but something that's difficult to describe -- something like the sound of a bigger (as in lower) whistle. And, as I said, I don't know if the thicker walls have anything to do with it.

The wall thickness of the tube certainly plays a part in hole size and placement, but I don't believe that thick-walled tubes necessarily require large holes... it's all a matter of placement that determines the necessary hole size.

I meant for holes in the same positions. The thicker walls lead to greater resistance.

As Raindog, I'm also curious what others have to say, especially some of the more experienced whistle wrights/smiths.

[Lorenzo]

What's the effect (particularly in a wooden whistle) of thicker or thinner walls on the behavior, timbre, etc. of the whistle?

With U-pipes and flutes, wall thickness is also known as "chimney height" of the tone hole. If I were to thin the wall of my flute or chanter (even scalloping the surface at the hole), from the outside, this (I'm advised by the experts - Ted Anderson) would change the tuning of the note. The chimney (tone hole) is just an extention of the bore, or tuning length of the note. Some chanters do have scalloped fingerholes, but the fingerholes are sized after the scalloping is done to arrive at the correct pitch. Yes, larger fingerhole equals louder plus higher pitch. Some U-pipe chanters have very large fingerholes...these are known as "banjo blasters" -Davey Stephenson/Peter Hunter. The "timbre" would be affected differently by different woods. After a certain wall thickness, it seems any more thickness added to it would act as a mute to the tone and volume. Isn't a wall thickness that is just right, one that absorbes the overtones and leaves you with a pure tone?

[cwmwl]

First I want to stress that I am not an expert on the issue. But my studies in physics has taught me some things that might be valuable on the subject.
The sound of a whistle is not produced by air passing through the whistle, but by air passing over the whistle body at the blade, thus causing a stationary wave inside the whistle. Now the quality of that wave causes the purity of the sound. So far so good.
Closing the holes does nothing else but "lengthening" the whistle body. Now look at this fact from the inside of the whistle: the most agreeable tone I expect from a perfectly smooth inside wall. This perfectness will naturally be disturbed by two fact:
1) Parts or the fingers protruding inside the whistle, caused by too large fingering holes on too thin a wall.
2) Fingering holes that cannot be locked evenly with the inside wall, this being caused by too small holes on too thick a wall.

From all this I would conclude, that not the wall thickness by itself, nor the size of the holes alone can be held responsible for the quality of the sound of a whistle.

As to the loudness of a whistle, I tend to hold the size of the window at the blade responsible for that. That's where the actual sound is generated. Found out this by experimenting on taping the window in order to quiet the sound.

Wilfried

[Lorenzo]

"Sound" is a general overall term in English. "Volume" and "tone" would be elements or divisions of that sound. Several things contribute to the volume (sizes/shape/postion of blade and window, size of tonehole, rate of air passing through). Several things also contribute to the tone or timbre of the instrument. The type and thickness of material is significant. If wooden, the type of wood significantly affects the tone too. Smoothness of bore certainly affects the sound to a lesser degree. Conical vs. cylindrical also affects volume and tone.

Ponder this: dense tempered glass has a smoother bore than wood or metal. Take the mouth piece off of a whistle (wooden or metal) and place it on a glass whistle with same size bore. Results? Less volume and darker tone/timbre. The density/thickness of the material is probably what makes the most difference, although in wood, it's not always denisty. There's some other so-called mysteries.

So, in wooden whistles, wall thickness would affect timbre and pitch (chimney height factor), and I'm guessing that in the extreme...volume to a lesser degree because of the possibility of the muting factor. Size and shape of bore would also affect volume, tone, and pitch. All this apart from the affect of the blade shape/position and size of window.

[glauber]

It would be nice to hear from a builder, or if someone made 2 whistles, one normal the other exageratedly thicker.

My expectation is it wouldn't change the timbre much, but it would affect the tuning.

[Thomas-Hastay]

Jerry wrote:"Whats the effect of thicker or thinner walls on behavior, timbre etc."

Without considering material or surface texture and sticking precisely to the question, the "effect" is on 1)Harmonics, 2)Register "phase shift" and 3)Loudness.

A deep narrow tonehole will favor low frequency harmonics(reedy,nasal tone) because the weaker energy high frequncy harmonics can't make it through the "bottleneck". A larger tonehole or a tonehole with a wide internal undercut provides less resistance to the air column to alleviate this character trait.

Deep narrow toneholes provide a serious design flaw in instruments that need to overblow the harmonic registers. As the internal pressure increases in the upper registers, the air column "pushes up" into the tonehole lattice to increase overall cubic volume and the scale goes very flat. Recorders with deep toneholes use the technique of "pinching" open the thumbhole to correct this "Tonehole Lattice Flattening Effect" but Whistles don't use this feature.

Using deep toneholes allows the designer to bring the fingerholes closer together in a keyless design because each tonehole is a "bore lengthener". One example of this use would be the last tonehole in a low whistle, to move it closer to the voicing without losing "apparent length".

Another "defect" of deep toneholes is in the natural phase-shift of the anti-nodes between registers(anti-nodes are places in the bore of highest vibration needed for correct tonehole placement). In Recorders, this phase shift needs only be corrected for in one upper register with the pinched thumbhole, but whistles use 3 or 4 registers and the high pressure nodal phase-shift in the upper registers would cause the toneholes to be "out of place" or silent.

Lastly, small narrow toneholes reduce loudness and, as was metioned of bagpipes, can create large differences in loudness if combinations of small/narrow and large toneholes are used in one instrument. Thickness can be used for overcoming design obsticles too, like the low whistle finger stretch I mentioned and for changing tone color, but like all acoustic features, there is always a give/take relationship.

[Flyingcursor]

I thought you meant walls, like "bulkheads" .

[Zubivka]

whistles use 3 or 4 registers and the high pressure nodal phase-shift in the upper registers would cause the toneholes to be "out of place" or silent.

I'm impressed by those who hover regularly in this stratosphere. I venture only seldom to the 4th register, i.e. d".

Now... since you mention 4 registers, I wonder:

Does anyone ever use the 3rd register with its offset fifth? (i.e. overblowing d'--all holes closed!--to get an a' , e' to get in b'...)

[bjs]

Does anyone ever use the 3rd register with its offset fifth? (i.e. overblowing d'--all holes closed!--to get an a' , e' to get in b'...)

I started doing this on my silkstone and gave it up in favour of the more usual fingering. Presumably this is how a tabor works.

[serpent]

There are several effects related to wall thickness, but the main one that comes to mind right now is called the "chimney" effect. The extra height of a tonehole adds a small amount to the effective length of the whistle body, which must be compensated when doing hole placement calculations. To see this effect in action, download Peter Kosel's "flutomat" calculator and try the same flute formula with different thicknesses of wall. It becomes very evident that wall thickness has an appreciable effect! It's also why using simplistic calcs like percentages of hole diameters and placements, quits working when your material on one whistle doesn't match that on another, and you wind up with an out-of-tune scale, or octave shifts screw you up!
serpent
(who has probably screwed up more whistles than Jessie Kislin owns! )

[Daniel_Bingamon]

Yes, Closed hole correction becomes a big factor in thick walled whistles.

It also lowers the local cutoff frequency of each hole. This causes the sound radiation pattern to change at lower frequency. You can compensate by using wider toneholes. This causes wider spacing and therefore encourages the builder to make conical bores to keep things within reach.