interesting article

[uilleannfinlander]

http://www.bretpimentel.com/does-materi ... -to-agree/

[Pipewort]

There was another thread recently that nearly made me reply thus; but to annotate my reply accurately, I will have to delve a bit on the BBC website.

There was a program on Radio 4 that examined tone, viz a viz materials. Particularly in the context of fiddles/violins, that is Stradivarius instruments, as examples. Fascinating, with contributions from players, restorers, physisists etc. I hope it will be in the archive, as it had much to add to whatever the discussion was in the 'lost thread', which had moved on by the time I heared what was said before replying, and then to this question.

I will search, and post if successful.

Pwt

[rorybbellows]

I'd agree that alot of the precieved tone difference is psycological in that you hear a difference because you think you should. I dont expect the scientific evidence will change the mind of those who believe that the material does make a difference for the reasons given in the article.Even the work of Dr J Backus will probably be ignored regarding hollow stocks.

RORY

[Hans-Joerg]

I find the article problematical in two ways:
1. Flutes and reed instruments are investigated by scientists
(!scientists!)
in the same way. Of course they all are woodwinds (and also the sexyphone) but the "soundwave production" in flutes and reed instruments is completely different:
http://www.gmi.edu/~drussell/Demos/wave ... otion.html
(scroll a bit)
There are no pressure differences in flutes. Flutes produce transversal waves whereas reed instruments produce longitudal waves and therefore the "friction" between the wave-particles and the bore surface is higher (and IMO affects the sound much more). To compare flutes and reed instruments is a bit like comparing apples and peas. In terms of musical theory it makes more sense to compare oboes/uilleann pipe chanters with brass instruments.

2. All is about material but nothing is said about the (material inherent) surface quality (size of the pores). IMO the smoothness of the bore is much more important than the material alone.

BTW, I heard an uilleann pipe concert pitch chanter from beechwood made, reeded and played by the same person (Andreas Rogge) recently. He had bought the log simply in a crafts-supermarket (years ago of course). Like with his boxwood or plumwood chanters he had oiled the bore. It sounded brilliantly. I could not hear a difference.

[billh]

The article, and most of the discussion on this topic in this thread as well as elsewhere, continues the confusing practice of mixing discussion of soundbox instruments with wind instruments.

It also jumps from discussions of instruments made from extremely similar materials (brass versus silver and gold alloys) to instruments made of wildly dissimilar materials.

I think this tends to muddy the water such that very little is conveyed to temper readers' pre-existing beliefs.

It seems clear to me, however, that those who claim that tonal differences in woodwinds are "obviously" a result of intrinsic material properties are wrong, as are those who claim that intrinsic material properties have no audible effect. It's easy for the acousticians to pick holes in the naive arguments of musicians, just as it's easy for experienced musicians and makers to pick holes in the equally naive explanations of scientists using oversimplified models and flawed experiments. The reality, IMO, lies somewhere in-between. It is actually fairly easy to demonstrate that minor surface changes to woodwind instruments produce measurable changes in acoustic behavior - which undermines the simpler arguments against wall material effects.

Unfortunately the public discussion tends to have all the rhetorical subtlety of "talk radio"...

Bill

P.S. - Hans Joerg: actually there are considerable pressure changes in flutes just as there are in pipes - that's the nature and definition of a standing wave, where pressure and velocity are 90 degrees out of phase with one another.

P.P.S. - Rory: As far as I know there's nothing in Backus that contradicts what I've said about hollow stocks. Can you give a specific reference to what you're talking about?

[Hans-Joerg]

Bill,
of course there are pressure changes. I meant them extreme pressures, that you actually can feel: You have to squeeze the bag a bit or "press" into a trumpet, whereas you gently blow into a flute. As I understand it, in a flute the pressure is a little more or a little less than the environmental pressure while within the bore of a chanter or oboe it changes/oscillates around a higher level. After the opened hole it hits the evironmental pressure and continues (like tones of string instruments) as transverse wave?

[pudinka]

Even the work of Dr J Backus will probably be ignored regarding hollow stocks.

P.P.S. - Rory: As far as I know there's nothing in Backus that contradicts what I've said about hollow stocks. Can you give a specific reference to what you're talking about?

As far as I know, there's nothing in Rory that contradicts what you've said about hollow stocks. His statement does not mention what you've said, nor does it say anything about hollow stocks. Can you give a specific reference to what you're both talking about?

[uilleannfinlander]

not trying to throw fuel on fire , just found this from other piping forum.

[rorybbellows]

Even the work of Dr J Backus will probably be ignored regarding hollow stocks.RORY

Sorry,I should have made myself clearer. What I was refering too was the paragraph in the article where Dr Backus proves that no sound comes off the vibrating wall of a woodwind instrument which proves that no sound comes off a hollow mainstock. As I said before what is probably happening(and I don’t want to create a false dichotomy so there may be another answer)is that the mainstock is acting as a driver and passing vibrations into the bag which acts as the resonator.This explains why you hear muting of sound when you put your hand on the mainstock .The hollow mainstock is low impedence and is easily muted .This also explain why you don’t hear any difference when you do the same to a solid stock as the solid stock is of higher impedence and is not so easily dampened and all the vibration travel into the resonating bag.You are getting all the “extra sound”transmitted to the bag with a solid stock.The worst case scenario is a hollow stock with a bass regulator screwed on the side as this mutes the light hollow stock interrupting the flow of vibrations ,this does not happen with a solid stock.

RORY

Ps Bill, I know you wont agree with these ideas ,so could you explain why you think a hollow stock is a resonator and gives off audible sound.

[billh]

I am very much unconvinced that a bag acts as a resonator. There is a huge amount of damping on the bag and the walls are far from rigid. However I am open to someone demonstrating it to me!

However I don't really think that a hollow stock acts as a resonator to any observable extent either. There may be some very minor effects but I doubt they can be detected.

Where I disagree is about the notion that the hollow stock doesn't "give off" any significant sound. The reeds themselves make considerable noise, as is illustrated every time someone tests the crow of a drone quill. The hollow stock doesn't serve to amplify the sound that way a soundbox does, but its thin wooden walls are quite transparent to sound, and the reeds can be heard vibrating through the wood. In this way the stock "gives off" sound in the same way as any acoustically transparent object.

Put it this way - if 3 or 4 millimeters of light wood didn't transmit sound, nobody would ever have complaints from neighbors about practicing pipes!

I hope this clarifies my thinking regarding how the observable sound from a hollow stock may be explained without violating the laws of physics

best regards,

Bill

P.S. - some may counter with the observation that a cylinder is quite a rigid form and thus is less subject to movement than an apartment wall, which acts like a huge diaphragm. This effect does mean that a cylinder is relatively opaque to low frequencies, but the high frequencies from the reed quills still get through, as the cylinder's walls are free to move in higher modes which move a significant volume of air with much smaller (but faster) deflections. Hemispherical domes make very poor woofers but excellent tweeters...

[elbowmusic]

I think I should help to help point out a difference between what Dr. Backus was testing and a hollow mainstock: Dr. B was testing if the body of the clarinet was giving off sound, which it apparently wasn't. The equivalent here is chanter. The mainstock is not the body of the instrument. The equivalent with a clarinet would be the players mouth (I guess), which Dr. B was not testing.

Also, maybe someone can help me with this part, but I think when a drone is playing, there is sound coming out of both ends of the drone. (?) So the mainstock would be bombarded by the drone sound happening inside it.(?) I would imagine a hollow mainstock would vibrate because of that, and that would probably affect sound going back out the drones to the outside. My physics knowledge is very shaky here, someone help me out.

Nate

[elbowmusic]

Billh beat me too it!

[MTGuru]

There are no pressure differences in flutes. Flutes produce transversal waves whereas reed instruments produce longitudal waves

Hmm, this seems wrong to me. Sound waves in air are compression waves (longitudinal). Whether the air is all around you, or inside an instrument tube, makes no difference. The source of the vibration of reed instrument or flute makes no difference, whether the sound generator is a physical reed or the "air reed" of a flute. They both impart pressure pulses to the air column which are independent of the vibrational geometry of the generator.

Any transverse vibration of an air column would be constrained by the walls of the tube anyway.

http://www.phys.unsw.edu.au/jw/flutes.v ... .html#time

Yes, the closure of a physical reed creates a pressure maximum at that end, whereas the open embouchure of a flute's air reed creates a pressure minimum. This difference results in different standing wave behaviors in the tube. But the vibration of the air column is longitudinal in either case.

At least, that is my understanding. If I am wrong, can you point me to a good source to correct me? Thanks!

[pancelticpiper]

I am very much unconvinced that a bag acts as a resonator. There is a huge amount of damping on the bag and the walls are far from rigid. However I am open to someone demonstrating it to me!

I don't really think that a hollow stock acts as a resonator to any observable extent either. There may be some very minor effects but I doubt they can be detected.

In the GHB world it seems that most good players agree that the bag makes a significant difference in tone. Most agree that a sheepskin bag gives a fuller tone, while cowhide bags and especially synthetic bags dull the tone. While I can't imagine how this could be possible, I've experienced it myself, when I switched from a GoreTex bag I'd been playing for a few years to an L&M "elkhide" bag. The chanter and drones both were louder and fuller-sounding with the leather bag. And many good players have experienced the same thing when switching from an "elkhide" bag to a sheepskin bag. Why? I have no clue.

About stocks, certainly on Scottish pipes it's been shown that switching a chanter between stocks of various diameters (changing the hemping to suit of course) results in changes in the tuning of the chanter's scale, especially notes in the middle of the range, the D and E (what would be G and A on the uilleann pipes).

Drones also can sound fuller and be more stable when played in larger-diameter stocks. That might be related to the uilleann hollow-stock effect.

[Hans-Joerg]

MTGuru,
you are right. The soundwaves within flutes are longitudinal waves. All sound that spreads in air (and other gases) are longitudinal waves. My understanding and perception of a transverse wave was wrong.