Thanks for your comments.
I may be mistaken, but you seem to require that theoretical calculations be accurate, and if they arenít, they are of no practical use. For instance,
You sure must remember that the calculation for cavity in your paper do not completely go
along with my testing results.
And the are more of theoretical interest as of practical use for construction.
The value of theoretical calculations is often more in the understanding they allow than in whether or not they are accurate. Sometimes all it takes is an adjustment, or a fudge factor, in order to account for difficult issues, but again, the real value in these calculations is in the way they illustrate the physical mechanisms at work, allowing us to extrapolate our knowledge to areas not covered by experiment. We then master a physical phenomenon, allowing us to possibly enhance its expression in what we build. In the paper, I do explain the sources of error Iím aware of. If you havenít already, you might want to read the section ďComplicationsĒ that lists some of these inaccuracies, but Iím sure youíre aware of these things. I think the greater value of the paper is in allowing an understanding how resonance in chambers becomes more likely for the higher pitched reeds, and how lower overtones of the musical tone become more susceptible to cavity resonance as the pitch increases. Such an understanding eliminates a lot of experimental investigation. Perhaps it would be worth sharing your experimental data with me, and we can look at the calculations together.
Your say tensity and mass is the only thing to take into account for calculation.
I think you missed the main point of my last post, which was to evaluate a possible physical mechanism (wood resonance) that would explain the effect changing wood material in a concertina has on musical tone. I clearly did not say what you claim above. Do you have any comments on my reasoning, in the purpose of my post?
You are not right in this respect, there are much more physical aspect of a sheet of wood tho be taken in account.
grain direction homogeneity of grain cellular structure and much more.
I agree that the speed of sound varies with grain direction in wood. Itís interesting to first note that this fact is a direct result of the fact that the Youngís Modulus varies with grain direction, which again illustrates the general principle that the square root of the ratio of stiffness to density is, practically, the only material property that influences the natural frequencies of vibration. I say ďpracticallyĒ here because, in my previous post, I simplified things a little. With some vibrations, Poissonís Ratio also comes into play, in a smaller way, and this ratio is pretty much the same among most construction materials. Also, please note, Iím NOT saying that this factor is the only material property that explains ALL acoustic effects. Itís interesting to note that Youngís Modulus in the longitudinal direction for most woods is from roughly 10 to 20 times larger than that across grain. One exception is Oak, with a ratio of about 2.5. For Spruce, choice material for the top plates of string instruments, itís from 13 to 24. Since the density is the same in both directions, this means that the speed of sound will be greater along the grain by a factor about equal to the square root of this ratio say, about 3 to 5. This is one reason why the aspect ratio of bowed string instruments is approximately 3 Ė sound moves out to the edges more or less uniformly, enabling many mixed vibrational modes. An added complexity is that the sound speed varies more or less continuously with grain angle, achieving the above maximum and minimum at zero and ninety degrees. (Let me also mention that, for sound waves in wood, one uses the dynamic Youngís Modulus, which is about 10% greater than the static value, and it varies inversely with moisture content, but this is getting boring.)
In any event, letís speculate and suggest that this non-homogeneous property of wood might explain why different woods behave differently in a concertina. To explore this, Iíd first like to ask Frank, Dana, Richard, Chris, and other builders if they orient the grain in preferred directions when building. If they donít, Iíd tend to think the effect isnít important, since so little can get by these craftsmen :-)
Without knowing this, Iíd have to guess that thereíd be little influence of grain orientation in the reed pan or action board of radial reed layouts (Wheatstone?). With parallel arrangement (Jefferies?), one might choose to orient either the long axis or the short axis of the cavities with a particular grain orientation. After building several concertinas and evaluating their musical tones, conclusions may be drawn. Thatís a lot of work. Still in my guess mode, I donít see much merit in this, and one good reason for my skepticism is that, with all the cavities attached to the reed plate, the resulting structure is much more rigid than the simple board, and so too with the action board, which often has another rigid plate attached (to guide the buttons). These additional members, I think would bury a 40 % change of sound speed with grain orientation.
If we really want to know the answer to the question of the original post, a good experiment to do would be simply to measure the amplitude of wood vibration in the different wooden members. Knowing this number would surely spawn a lot of thinking. But Iím not inclined to do such an experiment until Iím more convinced, for whatever reason, wood material is important.
The same apply s for calculation on other wood parts of reed instruments.
I also made test with different wood cases as well.
Spruce makes a big difference to other wood.
So I believe Dana and my experiences go in the same direction, still for accordions one should not make the mistake
to think there is a major influence or difference if different types of wood are used.
You have me confused. Do you think wood material is important to musical tone in concertinas or not? Perhaps my memory fails me, but as I recall, didnít you once make accordion reed cavities from balsa wood and found no noticeable effect?
In any event, I appreciate your comments.