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Thread: Wood Anatomy

  1. #1
    Registered User Denis Kearns's Avatar
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    Default Wood Anatomy

    I had intended this comment for the “tone rite” thread, but it closed before I had completed the post. Even so, I would still like to share my comments on wood anatomy for those interested. (especially since I took the effort to write it, instead of playing my mandolin!)

    As a botanist, I spent some time in school learning and thinking about the structure of wood. Still do occasionally when I gaze at a tree or an interesting piece of wood. In a tree, wood (called xylem by us botanists) is composed of a mix of cell types; those closest to the bark function to transport water and minerals from roots to leaves. This sapwood contains a few living cells, some fibers, but is mostly dead, tube-like cells of various dimensions, connected into “water pipes”; the bigger water pipe cells are easy to see in a piece of oak cut perpendicular to the trunk. In heartwood, all the cells are dead and hold waste products deposited while living cells were still present. Remember that plants, just like you, need to eliminate waste products; they do this by depositing their “shit” (sorry for the technical term) into older wood cells. Depending on the species of tree, you get heartwood of different colors and chemical make-up. Plants are diverse chemical factories and this is why we get wood with an amazing range of tonal properties.

    Given this architecture and mix of chemistry (very, very simplified above), it is not surprising that wood properties can change as it ages or as wood is subjected to external forces. That being said, I would need a lot more statistically valid data before I would spring for one of the discussed tone-altering machines. If I was doing the research (which I’m not), I would subject pieces of wood to the machine and compare wood anatomy and chemistry before and after. For a lasting effect on tone, I would expect to see some demonstrable alteration in cell architecture and/or chemistry. For those interested, there has been a lot of wood anatomy research as part of understanding Stradivarius instruments. Wood is pretty cool. A recent study estimated that there are about 73,000 different species of trees. Given that we currently use only a small handful to build musical instruments, I expect some fun discoveries in the future.

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  3. #2
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    Default Re: Wood Anatomy

    One of the best summaries of wood properties for string instruments is the article by Daniel Haines in the Catgut Acoustical Journal for Nov., 2000. The reference follows:

    Haines, D. The Essential Mechanical Properties of Wood for Musical Instruments; CAS Journal, Vol. 4, No. 2 (Series II); pp 20-32 (Nov. 2000).

    Haines' article has several tables and graphs which illustrate the dramatic variation of physical properties, even within species. Or maybe I should say "...especially within species". There are other worthwhile papers about the properties of wood for instruments, A good introduction to the properties themselves is in the Fletcher & Rossing text:

    Fletcher, N.H.; Rossing, T.D.; "The Physics of Musical Instruments, 2nd Edition", chapter 22; Springer, NY, 1998. ISBN 0-387-98374-0. Iirc, there is a paperback edition now.

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    Default Re: Wood Anatomy

    guitar player magazine had an article years ago on how wood decays at a molecular level....over decades the wood cell dries out ..therefore transmittiting sound
    more fluidly. it finally dissinagrates to the point where it can no longer take the pressure and stress...and simply gives out. im really amazed that srtatavarios and even old martins have lasted this long. ...there is a lot of string tension going on here.along with being bent and weather and humidity... there is a limit ... 4 or 5 hundred years .....who knows ..but they wont last forever.

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    Registered User sunburst's Avatar
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    Default Re: Wood Anatomy

    Quote Originally Posted by jherm View Post
    guitar player magazine had an article years ago on how wood decays at a molecular level....over decades the wood cell dries out ..therefore transmittiting sound
    more fluidly...
    Not sure what the article said or how it was stated, but wood does not continue to "dry out" as it ages. It reaches equilibrium with it's environment and fluctuates in moisture content in response to changes in it's environment.
    The very fact that antique violins have survived so long is evidence that wood can be very durable over time if well cared for. Also, instrument design is a large contributor to longevity.

    Not sure what they mean by "transmitting sound more fluidly", but sound transmission through solids (like wood) is but a minor contribution to the sound we hear from an instrument. We hear the sound that is transmitted through the air resulting from wood and air moving in their normal modes of motion.

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    Default Re: Wood Anatomy

    Quote Originally Posted by sunburst View Post
    Not sure what they mean by "transmitting sound more fluidly", but sound transmission through solids (like wood) is but a minor contribution to the sound we hear from an instrument. We hear the sound that is transmitted through the air resulting from wood and air moving in their normal modes of motion.

    You're not wrong, but you are kind of missing the point.

    In order for the wood to move the air, the strings need to move the wood, which requires sound being transmitted through the wood. Therefore, the ability of the wood to efficiently transmit sound is important for volume and sound quality of the instrument.

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    Registered User sunburst's Avatar
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    Default Re: Wood Anatomy

    Quote Originally Posted by milli857 View Post
    You're not wrong, but you are kind of missing the point.

    In order for the wood to move the air, the strings need to move the wood, which requires sound being transmitted through the wood. Therefore, the ability of the wood to efficiently transmit sound is important for volume and sound quality of the instrument.
    Well, that's not exactly how it works. I'm running out of time, but the simple version is:
    string motion excites the top which then immediately excites all other parts of the instrument and the air within to move in their normal modes of motion. All parts interact with all other parts and though sound does travel through solids, it is not an important contributor to the way acoustic stringed instruments convert string motion to sound.

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  11. #7
    The Amateur Mandolinist Mark Gunter's Avatar
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    Default Re: Wood Anatomy

    Very informative posts from Denis Kearns, Dave Cohen and John Hamlett here, thanks.

    As John pointed out, wood does not simply continue to "dry out", it reaches a temporarily stable moisture level in relation to the relative humidity of the atmosphere. Temporary, in that as the RH changes, the moisture level in the wood changes. Anyone may perform experiments to test this fact by purchasing a moisture meter and taking regular readings of the moisture level in a piece of wood over time.

    And "sound traveling through wood" is but a small part of what creates the sound from your instrument. Anyone may perform experiments to test this fact by attaching a string or strings to a block of wood and plucking the string; then, attach a string or strings to a wooden box with sound hole and notice the difference in volume, etc. when plucking the string(s) as compare to the former. The box is more than just wood.

    The article mentioned, with no concrete references given, I would consider to be incorrect on several points if it says what jherm remembers it saying. No offense to jherm, or to the article's author, but I wouldn't trust that information at all.
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    Default Re: Wood Anatomy

    I’m not sure why this refuses to die. For some reason we want to believe that old wood is better, that it “plays in”. The superiority of old instruments, the violins and other instruments by Stradivarius and Amati, etc…, was exposed as myth long ago in double blind studies.

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    Default Re: Wood Anatomy

    Quote Originally Posted by lowtone2 View Post
    I’m not sure why this refuses to die. For some reason we want to believe that old wood is better, that it “plays in”. The superiority of old instruments, the violins and other instruments by Stradivarius and Amati, etc…, was exposed as myth long ago in double blind studies.
    I don't want to go too far down the rabbit hole here, and I have no scientific input to offer. But, as a fiddler first, I've had the pleasure of playing many different instruments of different ages and provences. Perhaps to the ear of the blind listener, the difference is imperceptible, but to the player it definitely isn't. For a violinist or fiddler, the feel of the vibrations and the tonal response shape your use of the bow. Certainly there is variation in how various woods transmit those things. And ot shapes both the sound of the instrument and the sound of the player. Part of this will always be the human element, and some of us are tuned in to this. It IS anecdotal but only because there's no scientific way yet invented to account for this. Many really good players, and knowledgeable luthiers can't just be wrong. As a part time arborist and woodworker myself, I can assure that these qualities can be measured in a form in various woods.

    My wording is probably off, but hopefully it conveyed...

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    Default Re: Wood Anatomy

    I tread lightly here, but let me try and clarify the argument. In the 80s, a lot of research by the Catgut Society and others tried to analyze sound in instruments. I worked in the industry, and read much on the subject. It was a given among musicians that older instruments sound better, but why? Part of it is surely the quality of the tonewood, and instrument design, but what else is going on? We knew our ears were not wrong.

    Yes, the wood dries out, but reaches an equilibrium with the ambient humidity. However, some electron microscope studies revealed that the top layers inside the sound chamber began to compress with the bombardment of sound waves produced in the confined area. What is coming out of the soundhole(s) is only a partial of the Db levels produced, which are quite high inside the chamber. As they reverberate, they bombard the wood cells, and compression is the result.

    We can try to arrtificially speed up this process, but I'm not sure if the various contraptions touted to produce results have the same effect as years of playing. Maybe, maybe not. Time may be the decisive element. That, and the various vibrating elements of the pieces as they are excited, physically, together. I think the jury is still out.

  17. #11

    Default Re: Wood Anatomy

    The OP is, perhaps, overthinking things. Much more likely in wooden instrument aging are more macroscopic effects like fracturing in glue joints and more mechanical damage to the wood itself. Chemistry might indicate nothing where a density change or a modulus change might be related to things overtly sonic.
    However, I’m told that actual measurement doesn’t validate guess and anecdote.

    That’s nice, because, as in so many sad applications, our precious things might decay, rather than improve, and we could be told that, like car tires, or pharmaceuticals, that mandolins need to be trashed after a few years…

  18. #12
    Registered User sunburst's Avatar
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    Default Re: Wood Anatomy

    There are slight changes in wood as it ages. An example is the evaporation of hemicellulose, a component of wood that does not contribute significantly to stiffness and thus reduces wood density as it evaporates, leaving the wood in an instrument with perhaps a more favorable stiffness to weight ratio... of perhaps a worse stiffness to weight ratio. As for antique violins being superior to new and whether the player can tell in a double blind test there is this.

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    Default Re: Wood Anatomy

    I have always held a fascination with wood. Not just for instruments, but certainly a great part for instruments. While at Gibson I was sent to the “Wood University” at Gibson. Fortunately it was held in Nashville where I lived. I found the course to be very interesting and a wealth of knowledge from the experiences of over 100 years of instrument making. I am getting old and do not remember much of it anymore, but I still find it fascinating. I know Gibson had or may have a wood expert on staff that helps choose which woods to use for what instrument and which tones. By taking the woods, adhesives, finish material, dimensions of each part and the moisture level inside the wood to be very important in getting a certain model instrument to have a repeatable outcome in the models being built. Yes, there are some tonal differences from instrument to instrument, but it is a fairly small difference if each instrument in that model. By careful selection of woods and making each instrument in a model have the same dimensions and same body cavity, you can achieve a fairly consistent tone. It’s the same in mandolins and acoustic guitars and electric guitars. We had some very cool machines to get the interior of the board to a certain humidity level where air curing is not as efficient and takes much longer. That produced more consistent woods to build with. On our varnish mandolins we used uv light to cure the finish and the woods in our high end mandolins. Certainly every person has a different set of expectations sonically when choosing an instrument and for those with less experience playing an instrument, they may not hear it the same as one with more experienced ears. There are J45 players who feel that is the finest sounding guitar ever made. There are others who feel that way about a D28. Bob Taylor built a guitar from the wood in a shipping pallet, and it seemed to surprise a lot of people that it could sound as good as it did. It even sounded like a Taylor I am told. One of the more enjoyable things working with Charlie Derrinton was the amount of experimenting we did. I have far surpassed any scientific knowledge I may have, but I am enjoying this thread. Have a blessed day and enjoy this thread!
    Have a Great Day!
    Joe Vest

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    Default Re: Wood Anatomy

    i am sorry to hear that wood plays a very insignificant role in producing sound ......but you are probably right..... but dont try saying that to the santa cruz guitar co or to martin guitars .......who in 1 of there journals listed 16 different species of wood and there distinct differences in tonal quality. obviosly they think types of wood make a big difference in sound quality. whether it be old wood or new...the science of sound is simple enough but the science of wood and its effects on sound like our original article i think..........has a long way to go .........and kudo's to itzak perlman who is still making payments on his strad.....,,there must be something to it..

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    Default Re: Wood Anatomy

    For what it’s worth, and I’m sure there will be disbelievers (I’d have hear for myself), 10 or more years back NPR had a segment on violin comparisons, new and old. A Strad is what was being tested. Ended up that the Strad was not always choking the double blind test. Go figure.

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    Default Re: Wood Anatomy

    Carleen Hutchins herself had a paper in CASJ in which she re-evaluated some violin family instruments she had built ~10 yrs later when they had been returned to her for adjustment or some such. I don't remember the issue at the moment - would have to look it up. Iirc, she also evaluated some new instruments which had been given the speaker treatment (?). I'm fuzzy on the details, because it's been a good while. What stood out though is that yes, there were some differences in the amplitudes of some body resonances - maybe 10% or so. On the other hand, the conclusion was that the changes were inaudible. A reasonable conclusion. Human hearing is logarithmic, which means that the difference in what is heard is much smaller than the simple ratio of any two amplitudes. It really takes about a doubling of amplitude before human ears begin to hear much of a difference. Further, the difference in amplitude for air pumped In and out of sound holes or off of body surfaces is considerably smaller than the differences in amplitudes of the body modes doing the air pumping. Still further, not all body modes are monopole radiators; some body modes result in less air pumping than others do. In all, more good reasons not to get too excited about the potential of treatment gizmos to affect ~$300 worth of difference.

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  25. #17
    Registered User lowtone2's Avatar
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    Default Re: Wood Anatomy

    Quote Originally Posted by Mainer73 View Post
    I don't want to go too far down the rabbit hole here, and I have no scientific input to offer. But, as a fiddler first, I've had the pleasure of playing many different instruments of different ages and provences. Perhaps to the ear of the blind listener, the difference is imperceptible, but to the player it definitely isn't. For a violinist or fiddler, the feel of the vibrations and the tonal response shape your use of the bow. Certainly there is variation in how various woods transmit those things. And ot shapes both the sound of the instrument and the sound of the player. Part of this will always be the human element, and some of us are tuned in to this. It IS anecdotal but only because there's no scientific way yet invented to account for this. Many really good players, and knowledgeable luthiers can't just be wrong. As a part time arborist and woodworker myself, I can assure that these qualities can be measured in a form in various woods.

    My wording is probably off, but hopefully it conveyed...
    The musicians who participated in this famous study were beyond competent.

    https://www.science.org/content/arti...nd-sound-check

    https://www.science.org/content/arti...645.1659591116

  26. #18

    Default Re: Wood Anatomy

    Even back in the 1800s writers were already commenting that some of the reason Stradivarius and Cremona instruments were perceived as superior was survivor bias. The Strads and Guarneri instruments that were dogs had been thrown out long before.

    Confounding the issue even more is that the instruments have all had major maintenance and often major reconstruction through their lives. There are no 100 percent original Stradivari instruments. There is only one in all the world with the original neck. ALL of the others had their scale lengthened during the 19th and 20th centuries.

    Part of the reason for older mandolins and guitars being so revered is the corporate ownership of Martin and Gibson during the 1960s and 1970s produced poor quality instruments, churning them out to take advantage of the guitar fad. They were built too heavy in order to avoid returns, regardless of the effect on sound. The instruments of the 1920s, 1930s and 1940s were superior. Not because the wood aged, but because they were built better and lighter. With the return to better craftsmanship in individual luthiers and at some of the factories, the products of today often rival or exceed the old instruments.

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  28. #19
    The Amateur Mandolinist Mark Gunter's Avatar
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    Default Re: Wood Anatomy

    Quote Originally Posted by Mark Gunter View Post
    Very informative posts from Denis Kearns, Dave Cohen and John Hamlett here, thanks.

    And "sound traveling through wood" is but a small part of what creates the sound from your instrument. Anyone may perform experiments to test this fact by attaching a string or strings to a block of wood and plucking the string; then, attach a string or strings to a wooden box with sound hole and notice the difference in volume, etc. when plucking the string(s) as compare to the former. The box is more than just wood.
    Quote Originally Posted by jherm View Post
    i am sorry to hear that wood plays a very insignificant role in producing sound ......but you are probably right..... but dont try saying that to the santa cruz guitar co or to martin guitars .......who in 1 of there journals listed 16 different species of wood and there distinct differences in tonal quality. obviosly they think types of wood make a big difference in sound quality. whether it be old wood or new...the science of sound is simple enough but the science of wood and its effects on sound like our original article i think..........has a long way to go .........and kudo's to itzak perlman who is still making payments on his strad.....,,there must be something to it..
    It’s not that sound quality is not affected by the wood … the thickness, the density, the stiffness of a soundboard will definitely affect sound quality, along with the resonance from the sound chamber … but this is due primarily to the vibrating of the top as a whole, not the traveling of sound waves through the wood. Hopefully you can see the distinction.

    I’m not an expert, not a scientist, so I could be wrong and even more likely, imprecise in my language. The sound we hear travels through air. The large vibrations of a resonant sound chamber excites the air and creates highly audible sound waves.

    The sound waves or vibrations which excite the wood of the neck have a nearly negligible effect on the sound we hear … unless the excite a loose screw or fret or something that creates a nasty buzz. The way they excite the sound chamber, as a whole, is most important. And, as already noted, the thickness, density and stiffness of the sound chamber components, especially the top plate but all of them, are most important … and these features of those parts have to do with the wood from which they’re made. Wood species and characteristics matter a great deal IMHO
    Last edited by Mark Gunter; Aug-04-2022 at 6:30am.
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  29. #20

    Default Re: Wood Anatomy

    If the superiority of old instruments were due to wood aging or instruments being played in to open up then we would see similar effects with all old instruments. We don't. For every Gibson Lloyd Loar or Larson Brothers instrument or prewar Martin there are dozens or hundreds of Harmony and Regal and Oscar Schmidt instruments. None of these instruments are highly sought after for their superior tone qualities despite being the same age and similar wood stocks to the really great instruments. They are sometimes sought after for a funky or bluesy or cool factor. They are not claimed to have superior tone to good modern instruments.

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