I’m beginning to feel sorry for making the original post here! (just kidding) I have thoroughly enjoyed this discussion. Actually I began college with the intent of becoming an aerospace engineer, but after some difficulties with physics classes, I became a music major! I do still use my slide rule however to show my grandkids what a calculator used to look like! So I’ll leave the theoretical side of this discussion to you guys with pocket protectors full of pens, while wait with bated breath for the outcome of your research. In the mean time, I’ll ponder the material of my next high “D” whistle in a more metaphysical manor…
Some commonly held myths:
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That the physical properties of materials necessarily has an appreciable effect on the sound output, despite compelling evidence to the contrary. Plastic, wood, composite, metal, and even vegetable whistles, when carefully fashioned, very much sound like whistles. Clearly these materials have varying degrees of density, stiffness, tensile strength, anisotropy, surface smoothness, acoustic dampening, etc. and yet they all can sound like whistles. If these factors are relevant, then which ones? Diamond and Jell-O have different refractive indicies. Is this relevant? Prove that it’s not. Be cognizant of selective thinking.
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That any vibration or dampening effect of the whistle head or walls themselves have an appreciable effect on the final output. It’s widely assumed that whistles vibrate like the sound board of a violin or a drum head – far from it. Even if whistle heads/walls do vibrate, their contribution is miniscule. Go ahead, attach some strings to a whistle and strum it and see if it’s as loud as a guitar.
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That the degree of exoticness of a material is correlative with the complexity of a whistle’s harmonic content. Sorry, this is truly wishful thinking. It’s the same thinking as when we assume price is necessarily indicative of quality.
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Most importantly, that what we see immediately before us is the first place to draw conclusions (i.e., jumping to conclusions). For example, we may find a whistle is shrill, and say to ourselves, Oh it must be because it’s made from brass! It’s already been acknowledged by all the preceding whistlemakers that minute differences in voicing (whistle dimensions) significantly affect timbral and playing characteristics. Tweakers, myself included, will attest to this as well. Dimensional differences are not immediately apparent therefore it’s not the first place we look. In Medieval times, people had all sorts of wild ideas about the Plague before the actual cause was understood (which BTW, was recently brought into question again).
Far too much importance is placed on a whistle’s (and flute’s) material. We want the material to make a difference. It just ain’t so. It should not be the first place we go looking to make a difference in our playing.
That is correct, whistles do not operate like string instruments. The material affords dimensional characteristics. It the dimension characteristics that affect the tone. Whether a material is capable of being thick or very thin, the surface can be highly polished or dull and grainy.
A rough bore instrument can sound well but the boundary layer of the air see more disturbances and cause greater variances between upper and lower octaves. Much like the weird things that happen in RF, like a 1/4 wave shorted stub in an antenna circuit. To the average person the circuit board looks like has a dead short at the antenna connector - and that is true a DC levels up to a certain frequency - then at certain higher frequencies it doesn’t even see the short - if ignores it.
Edited for correct units in velocity…
The consensus seems to be that different materials make subtle, but detectable differences in the overall “sound” of whistles. This may be, in part, due to differences in the speed of sound in those materials. You can calculate approximate speed of sound in solids as:
V = (E/rho)^(.5) where E = the material’ elastic modulus and rho = material density. If the units for E are (lbs/sq. in.) and the units for rho are (lbs/cu. in.), the working formula is V (ft/sec) = (1/12)((E386)/rho)^(.5)
Material v (ft/sec)
Steel 16950
Brass 11760
Aluminum 17350
Blackwood 14360
CPVC 4190
With the exception of CPVC, there’s really not a large different in the speed of sound in different common whistle materials - that could be one reason the various, commonly used, whistle materials really don’t sound that much different. Since CPVC’s sonic velocity is much lower than the other common whistle materials, its “sound” ought to stand out from the crowd (so to speak), if material physical/mechanical properties really impact tonal characteristics significantly. How does your collective practical experience mesh with this line of thought?
I don’t see that we had a consensus, and I don’t see any relevance of a material’s speed of sound property. Why would that matter?
I think the geometry of the design is the prime factor.
But often choice of material has a secondary effect on this geometry:
For instance brass is quite hard, and a sharp lip can be easily obtained, which can make the whistle shriller. It also comes in quite thin walled tubes, compared to aluminium or wood, which has an effect on responsiveness. Wooden whistles often have thicker walls, and a deeper window, which has a big effect on the sound. And different materials may be finished quite differently, giving rise to differences in the boundary layer, and also in their property to have water beading on the surface.