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jdevries

New research: Power efficiency in the violin

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3 - falsify your data, write this paper, put out the press release claiming to know more about Strad than any dumb-arse violinmaker and pat himself on the back for putting them in their place.

 

Come on, the paper is not that bad. They did what they could with what they had. 

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I feel that there is some misunderstanding here about how physics articles should be evaluated and would also note that what the media (and one's own PR department) may do with a paper is beyond the control of authors and makes a lot of us cringe.  Wouldn't it be best to keep the rhetoric on a much shorter leash while this plays out? 

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Under "Data Accessibility" we read the simple statement "All data sources are provided in the electronic supplementary material." If anyone can find all the 470 data sources for Cremonese instruments, plus the various others for non-violins with some direct information about how they were individually documented, then I will climb back under my rock. :)

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Under "Data Accessibility" we read the simple statement "All data sources are provided in the electronic supplementary material." .....

 

Then you have to find the supplementary material and read it. Here is the link:

http://rspa.royalsocietypublishing.org/content/royprsa/suppl/2015/02/11/rspa.2014.0905.DC1/rspa20140905supp1.pdf

 

Read in particular "Section 5. Data collection". Alleging data forgery is a very serious acusation. If the acusation truns out to be true, it will literally end the academic careers of the authors. I can't think of any reason to risk one's career over violin's f holes.

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Then you have to find the supplementary material and read it. Here is the link:

http://rspa.royalsocietypublishing.org/content/royprsa/suppl/2015/02/11/rspa.2014.0905.DC1/rspa20140905supp1.pdf

 

Read in particular "Section 5. Data collection". Alleging data forgery is a very serious acusation. If the acusation truns out to be true, it will literally end the academic careers of the authors. I can't think of any reason to risk one's career over violin's f holes.

You beat me to the link by a nose, but I was busy sniffing the roses along the way  :P  :lol:

I see nothing exceptionable here.  Generating data by plugging secondary measurements and prior work into one's own equations is perfectly respectable and shouldn't raise any eyebrows.  Approximations and consequent ranges of error are explained. They detail where all the numbers came from.  It's a mathematical discipline, not art or something slippery like asking people how a violin sounds to them.  What's the problem?

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His name comes under the contributions for "interesting and motivating discussions."  That means that they talked to him, I guess.

 

I still don't see anything that would help make a better violin.

Don,,

I pulled out the best parts for analysis, don't be so quick to dismiss it.

I think that thy are telling us that because we copy strad's f's so carefully and we don't give way to evolutionary tendencies and mutations,

our violins don't have that supernatural power like strad's and Del Gesu's have.

When you make a violin,,,learn to sit back,, relax, evolve, mutate, let he knife flow through the wood, let the knife find it's own, resonance,

allow t to become one with the wood,, fear not your mistakes, and you to will be as great as strad.

I won't mention the fact that maggini's and Da salo's f holes were 10 mm longer than most others that came after them.

I guess that Da salos were so loud that the f's had to de-evolve before the human race became deaf.

(I love to make Da Salo's ,they are monsteously loud, but so are strad's even with those itty bitty f holes that they have.)

Quoting the paper...................

the violin's ancestors slowly evolved over centuries from simple circles to complex f-holes

By evolution-rate analysis, these changes are found to be consistent with mutations arising within the range of accidental replication fluctuations

from craftsmanship limitations with subsequent selection favouring instruments with higher air-resonance power.

violin design evolution

Owing to its long-standing prominence in world culture, we find enough archaeological data exist for the violin and its ancestors to quantitatively

trace design traits affecting radiated acoustic power at air cavity resonance across many centuries of previously unexplained change. By combining

archaeological data with physical analysis, it is found that as sound hole geometry of the violin's ancestors slowly evolved over a period of

centuries from simple circular openings of tenth century medieval fitheles to complex f-holes that characterize classical seventeenth–eighteenth

century Cremonese violins of the Baroque period.

By evolution rate analysis, we find these changes to be consistent with mutations arising within the range of accidental replication fluctuations

from craftsmanship limitations and selection favouring instruments with higher air-resonance power, rather than drastic preconceived design changes.

Unsuccessful nineteenth century mutations after the Cremonese period known to be due to radical design preconceptions are correctly identified by

evolution rate analysis as being inconsistent with accidental replication fluctuations from craftsmanship limitations and are quantitatively found

to be less fit in terms of air resonance power efficiency.

Did you get that?

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The major technical conclusion:

"By theoretical proof, experimental measurements and numerical computation, air flow at the perimeter rather than the broader sound-hole area is found to dominate the acoustic conductance of sound holes of arbitrary shape, making conductance proportional to perimeter length."

 

I'm sorry, but that just does NOT ring true to me on the most basic level of physics.  Long,skinny holes will have more resistance (i.e. less conductance) than round ones.  I don't care to slog thru all that greek stuff to figure out where it may have gone wrong, or maybe they just stated the inverse of their actual results.  

 

I had a violin with nearly round holes once, and the A0 was the highest, peakiest that I've seen, indicating low resistance.

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The major technical conclusion:

"By theoretical proof, experimental measurements and numerical computation, air flow at the perimeter rather than the broader sound-hole area is found to dominate the acoustic conductance of sound holes of arbitrary shape, making conductance proportional to perimeter length."

 

I'm sorry, but that just does NOT ring true to me on the most basic level of physics.  Long,skinny holes will have more resistance (i.e. less conductance) than round ones.  I don't care to slog thru all that greek stuff to figure out where it may have gone wrong, or maybe they just stated the inverse of their actual results.  

 

I had a violin with nearly round holes once, and the A0 was the highest, peakiest that I've seen, indicating low resistance.

What if we aren't talking conventional drag here, and the vibrating edges are injecting flow energy as drivers?,  In that case, the more edge, the more energy transfer maybe?  It also negates wall drag, as the peak periphery motion is moving faster than the center of flow.  I've been trying to visualize this as a boundary layer problem, and it's making my head hurt.....  ;)

 

Oh goody, there's going to be an area of turbulence somewhere in between.... [sound of pencil bouncing off wall]  :wub:

 

Okay, the thing's counterintuitive because of the free edge vibration, highest energy is at the edges, and they are radiating.   :)  Dunno if something else isn't messing with this, but taken by itself, it looks real. [Waddles off toward the coffee...]

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In the real world, an entity gets so much funding each year for whatever,

if the funds are not spent, less funds or no funds are received next year.

I've seen managers running trying to get rid of $25.000 in a week, if it is not spent before the end of the fiscal year,

they will receive that much less next year.

Hey ! Anybody need computers, desks, ergonomic chairs, attending a seminar, Quick !

When I see this kind of dribble,,,,

I can't help but wonder.

We need to spend money and you need something to do.

Maybe the navy is researching loud violins to deafen the enemy.

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and the vibrating edges are injecting flow energy as drivers?,  In that case, the more edge, the more energy transfer maybe?  It also counteracts wall drag, as the peak periphery motion is moving faster than the center of flow.  I've been trying to visualize this as a boundary layer problem, and it's making my head hurt.....  ;)

You're on it!

Think of the edges like little paddles, creating little itty bitty vortices, that expand and fill the room like giant tornadoes, cyclones if

you live in Brazil.

And that is why you can't wear a toupee when a strad is being played, it will blow your hair right off.

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In the real world, an entity gets so much funding each year for whatever,

if the funds are not spent, less funds or no funds are received next year.

I've seen managers running trying to get rid of $25.000 in a week, if it is not spent before the end of the fiscal year,

they will receive that much less next year.

Hey ! Anybody need computers, desks, ergonomic chairs, attending a seminar, Quick !

When I see this kind of dribble,,,,

I can't help but wonder.

We need to spend money and you need something to do.

Maybe the navy is researching loud violins to deafen the enemy.

Thank God that when this occurs, you can get things done that aren't usually blessed by the bean counters.

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The major technical conclusion:

"By theoretical proof, experimental measurements and numerical computation, air flow at the perimeter rather than the broader sound-hole area is found to dominate the acoustic conductance of sound holes of arbitrary shape, making conductance proportional to perimeter length."

 

I'm sorry, but that just does NOT ring true to me on the most basic level of physics.  Long,skinny holes will have more resistance (i.e. less conductance) than round ones.  I don't care to slog thru all that greek stuff to figure out where it may have gone wrong, or maybe they just stated the inverse of their actual results.  

 

I had a violin with nearly round holes once, and the A0 was the highest, peakiest that I've seen, indicating low resistance.

I agree with the A0 peak's height being high for a round hole but what about its width?  More drag resistance makes it wider?   They seemed to be interested in the area under the curve.

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I'm sorry, but that just does NOT ring true to me on the most basic level of physics.  Long,skinny holes will have more resistance (i.e. less conductance) than round ones. 

 

 

It's unfortunately worded in the paper but it is mathematically correct. It is physically fine too if you think in terms of very low pressure / speed, incompressible / irotational.

 

Fluid at some distance  from the boundary flows into itself. Stoke's theorem. Imagine ( barely ) shooting pebbles from a wide pipe vertically. A lot will fall back into the pipe.

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It's unfortunately worded in the paper but it is mathematically correct. It is physically fine too if you think in terms of very low pressure / speed, incompressible / irotational.

 

Fluid at some distance  from the boundary flows into itself. Stoke's theorem. Imagine ( barely ) shooting pebbles from a wide pipe vertically. A lot will fall back into the pipe.

This is complicated by the de facto boundary edge (lowest peak velociity) apparently being a turbulent zone located some distance between the hole edge and the center rather than at the solid edge.  We're dealing with an energy transfer (as pressure) rather than a unidirectional fluid flow as the answer.  It's weird and confusing, like vibrating stagnant pipes.

 

Is there a sonics/acoustics theoretician in the house?

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Italian ticklers......

  I find the term "sound Hole" something of a misnomer, at first glance  they would seem to let out the sound, but upon closer examination they are more related to pressure modulation valves, and, in violins especially , they serve as corpus flex enhancers, to put it in Mil spec terms....PMVs and CFEs    ...

 I would be more inclined to finish reading the entire paper , however the stark difference between the 10century shape of a tear drop and the 15thC   X form of the violin ...regardless of hole shape, leaves me wondering about why they are comparing apples to oranges , if only the hole shape had changed, instead of outline , construction methods ect., during that same time frame then,  I could consider it a more honest and unbiased attempt at understanding the effect and evolution of FF's .  

 while I do believe that a larger ratio of Air interaction surface AIS of the PMV  to ultmite hole volume or UHV  should result in an optimization of energy available to become sound, I'm not so sure about how the design was evolved , I see the evolution as more of a makers mark , that one thing classical makers might dare call their own ...but only after being firmly established,,, I can not see them a accidental , unless by that they only mean the design was generated around what works best ...

 I would think that today doing some experiments with design/effects of ff holes could be carried out fairly easy with 3D printers capable of producing exact copy's and only varying sound hole shape and location ...might not tell us what to do with wood though ... Probably at least a good thing for maker to consider ....F hole shape and size placement and edge qualities.... or FHSSPEQ....    

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First we had the actual Darwin theory of evolution through natural selection. Then some folks moved on to employ the theory to social change and came up with the dubious social Darwinism. Moving on again, we now have Violin Darwinism -- with folks seeming to assume that the people who actually made the early violins couldn't actually KNOW what they were doing. So some natural selection helped them out.

 

This kind or thinking is, of course, just conjecture, and is unworthy of the actual science in the work. There seems to be a postmodern idea that only our contemporaries are smart enough to work systematically and to understand the principles at work. The folks living in the 17th century didn't have the smarts to employ theory and an empirical method, working systematically and effectively. This is nonsense. A single fact casts it aside: Isaac Newton lived from 1642 to 1726.

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Italian ticklers......

  I find the term "sound Hole" something of a misnomer, at first glance  they would seem to let out the sound, but upon closer examination they are more related to pressure modulation valves, and, in violins especially , they serve as corpus flex enhancers, to put it in Mil spec terms....PMVs and CFEs    ...

 I would be more inclined to finish reading the entire paper , however the stark difference between the 10century shape of a tear drop and the 15thC   X form of the violin ...regardless of hole shape, leaves me wondering about why they are comparing apples to oranges , if only the hole shape had changed, instead of outline , construction methods ect., during that same time frame then,  I could consider it a more honest and unbiased attempt at understanding the effect and evolution of FF's .  

 while I do believe that a larger ratio of Air interaction surface AIS of the PMV  to ultmite hole volume or UHV  should result in an optimization of energy available to become sound, I'm not so sure about how the design was evolved , I see the evolution as more of a makers mark , that one thing classical makers might dare call their own ...but only after being firmly established,,, I can not see them a accidental , unless by that they only mean the design was generated around what works best ...

 I would think that today doing some experiments with design/effects of ff holes could be carried out fairly easy with 3D printers capable of producing exact copy's and only varying sound hole shape and location ...might not tell us what to do with wood though ... Probably at least a good thing for maker to consider ....F hole shape and size placement and edge qualities.... or FHSSPEQ....    

 

 

First we had the actual Darwin theory of evolution through natural selection. Then some folks moved on to employ the theory to social change and came up with the dubious social Darwinism. Moving on again, we now have Violin Darwinism -- with folks seeming to assume that the people who actually made the early violins couldn't actually KNOW what they were doing. So some natural selection helped them out.

 

This kind or thinking is, of course, just conjecture, and is unworthy of the actual science in the work. There seems to be a postmodern idea that only our contemporaries are smart enough to work systematically and to understand the principles at work. The folks living in the 17th century didn't have the smarts to employ theory and an empirical method, working systematically and effectively. This is nonsense. A single fact casts it aside: Isaac Newton lived from 1642 to 1726.

It doesn't look to me as if the physics and the historical musings were contributed by the same people, but then I seldom expect physics papers to be major watersheds of historiography any more than I read Shelby Foote for the gunnery ballistics.

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I feel that there is some misunderstanding here about how physics articles should be evaluated 

 

 

This is complicated by the de facto boundary edge (lowest peak velociity) apparently being a turbulent zone located some distance between the hole edge and the center rather than at the solid edge.  

 

Is there a sonics/acoustics theoretician in the house?

 

I'll stick with differential forms and let you do "reality", ... in violin research.  :lol:  :lol:  :lol:

 

All I'm curious about is how they stick a "shape factor" on a sound hole. Beats me but maybe I didn't drink enough today.

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Don... I have to ask ...does this though model work .? imaging a fluid filled tank... as air.... with a movable baffle, the violin, with holes of equal volume  ,but of different shapes and circumference, long thin , and then applying a given oscillation force, would the amount of energy transfer to the liquid ..or air, be greater than less than or equal to round to rectangular shape? intuitively I see less energy transfer with a circular hole because of reduced interface friction ...a higher edge to volume ratio ..should ...here's where I wonder ...transfer more energy per oscillation .resulting in more perceived volume?.  

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Don... I have to ask ...does this though model work .? imaging a fluid filled tank... as air.... with a movable baffle, the violin, with holes of equal volume  ,but of different shapes and circumference, long thin , and then applying a given oscillation force, would the amount of energy transfer to the liquid ..or air, be greater than less than or equal to round to rectangular shape? intuitively I see less energy transfer with a circular hole because of reduced interface friction ...a higher edge to volume ratio ..should ...here's where I wonder ...transfer more energy per oscillation .resulting in more perceived volume?.  

 

Water or air have only that much stiffness.

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Right. I have a very hard time believing that the ff holes are somehow (in any way) random.  I too wonder what the hell Zyggy is doing in the acknowledgements.  But I will love to read the article. 

 

 There's a long way between random and individually adapting characteristics to follow the same scheme on different arching profiles... I'm not getting how he arrived at such odd conclusions more so when the "difference" in design he speaks about is minor and progressive... From reading this article you would think there was a wildly inconsistent output coming from cremona's workshops...

 

I may be incorrect but, from what's left of the tools and templates from A.S's shop one can see that he compensated for arching differences with alterations to the ribbon (SLIGHT compensations as he was pretty consistent with his design schemes). Did Antonio not draw in the ribbon after the eyes were placed on? 

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Violadamore, the idea of flapping edges I don't think applies here.  The A0 frequency is far below any structural frequency of the plates.

 

Carl, I don't understand what you're talking about.  It seems to me you are describing inductance rather than conductance.  The conclusion clearly states "conductance" is proportional to perimeter length.

 

If that is the case, perhaps we should just squash all our plumbing flat to take up less room, since the conductance would be the same.  Go try it.

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If that is the case, perhaps we should just squash all our plumbing flat to take up less room, since the conductance would be the same.  Go try it.

 

I would. If I had their peculiar kind of fluid. :) :) :) 

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Let me share some of my experiences that just may help people understand how the Office of Naval Research could have been "involved" with this research.

 

Some 30 years ago I was employed by Schumberger (oil well services and exploration) in fiber optics research. My group was charged with developing optical fiber systems needed for high data transmission from new down-hole instruments designed to detect hydrocarbons (oil and gas). We also were investigating sensors (transducers) that used optical wave-guide (fibers) technology which surpassed existing detectors in sensitivity. The leading research group for this work was at the Naval Research Lab. They were declassifying their research and handing it over to industries. The NRL was in my opinion the premier researcher institution in acoustical research. They used this research for antisubmarine warfare (ASW). The ONR and NRL do fund other labs like MIT particularly in acoustics and particularly, sonar. Sonar needs to generate a powerful acoustical pulse with a particular range of frequencies that can pass far through water, reflect off a target, and return to a detector. So, I am not surprised that someone supported in a Naval research project would have been looking into acoustical sources. And, my guess, is that someone working in one of these projects saw an application to violins and put together this group of collaborators. 

 

I hope this sheds some light on how the Navy could have played a role - albeit a remote one. 

 

Mike

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The major technical conclusion:

"By theoretical proof, experimental measurements and numerical computation, air flow at the perimeter rather than the broader sound-hole area is found to dominate the acoustic conductance of sound holes of arbitrary shape, making conductance proportional to perimeter length."

 

I'm sorry, but that just does NOT ring true to me on the most basic level of physics.  Long,skinny holes will have more resistance (i.e. less conductance) than round ones.  I don't care to slog thru all that greek stuff to figure out where it may have gone wrong, or maybe they just stated the inverse of their actual results.  

 

I had a violin with nearly round holes once, and the A0 was the highest, peakiest that I've seen, indicating low resistance.

 

If that is the case, perhaps we should just squash all our plumbing flat to take up less room, since the conductance would be the same.  Go try it.

 

"Conductance proportional to perimeter length" is perhaps poorly stated in the paper.  Squashing pipes flat assumes constant area, but according to equation 3.5, conductance proportional to perimeter length applies to constant shape factor, not constant area, so that result seems plausible under a restricted (unstated?) condition.

 

Just what constant shape factor instead of constant area has to do with this paper is probably beyond my understanding, however.  If they are correct, it appears to me that they may have discovered something quite interesting, but you may well have a valid point.  It goes against my intuition too, although I don't trust my intuition in this case.  I'm afraid I'll just have to let experts in the field sort it out.

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