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A “Just Right” Guitar

The views expressed are those of the author and are not necessarily those of Scientific American.

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The four test guitars. Image courtesy of Kazutaka Itako and Satoshi Itako.

The MTV Video Music Awards are being broadcast tonight. Since 1984, these awards have recognized the top popular musicians, videos, and songs each year. Young musicians who dream of one day having their very own “Moonman” statue might be interested in getting the best guitar for their money. Luckily, science is here to help.

Kazutaka Itako is an electrical engineer at the Kanagawa Institute of Technology in Japan, but he has played the guitar since he was six years old. Satoshi Itako has a master’s degree in electrical engineering but works as a guitar fabricator. Together, the brothers have been investigating the optimal shape for guitars.

Experts have settled many questions surrounding the best shape for violins, but far less research has been done on guitars. The brothers’ preliminary work, presented at the Acoustics 2012 conference in Hong Kong in May, looks at one variable: guitar depth. They crafted four nearly identical guitars, ranging in depth from 58 to 98 mm.

They tested the four guitars using both objective and subjective measures of tone quality while a performer played open strings with two different strumming styles. They used an oscilloscope to measure the inclusion of harmonics, an index of the depth and richness of a tone. In addition, nine musically trained listeners rated the guitars.

The 68 mm thick guitar had the highest inclusion of harmonics, and six of the nine listeners rated it as having the best tone quality. The performer also reported that the 68 mm guitar was the easiest to play. The larger guitars were cumbersome, and the smaller one seemed unstable.

The Itako brothers have now moved on to the question of how the size of the sound hole influences the guitar’s tone. After that, they would like to study the effect of material. Kazutaka Itako says it is time-consuming and expensive to produce wooden guitars. He would like to determine whether a synthetic material, like fiberglass, could make instruments that are just as sonorous as wooden instruments.

Of course, at very high levels of performance, players’ individual tastes will probably determine the kinds of guitars they choose. The Itakos’ goal is to find the ideal dimensions and materials for a high-quality sub-professional instrument, allowing more amateur strummers to buy good instruments at affordable prices.

Evelyn Lamb About the Author: Evelyn Lamb is a postdoc at the University of Utah. She writes about mathematics and other cool stuff. Follow on Twitter @evelynjlamb.

The views expressed are those of the author and are not necessarily those of Scientific American.

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  1. 1. RogerPink 11:01 am 09/6/2012

    Harmonics are the key. Harmonics are lost during recording and so some of the tone is lost as well.

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  2. 2. toothinhand 11:10 am 09/6/2012

    Not to outwardly try to insult engineers and scientists, but if you want an article on the best sounding guitar you’re gonna end up looking
    like the guys from Big Bang. There is no best. there are to many variables to take into account. And you inevitably end up finding out that personal taste takes over.

    I’ve been playing guitar and working in music stores for over thirty five
    years. And been building them for more than twenty. There is no best
    guitar. Only best for the artist playing it. Then best for the song as it’s
    played by the artist. That’s why most of us end up owning more than

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  3. 3. Marcello09 12:56 pm 09/6/2012

    I agree with toothinhand, it’s hard to figure out what the Itako brothers are trying to accomplish. Guitar builders (a.k.a. “luthiers”) have known for centuries how different shapes, sizes, woods and varnishes influence guitar tone. Also, the tone will changes as the wood ages (most guitarists would say that it changes for the better).

    Additionally, using synthetic materials with acoustic guitars dates back to at least 1966, when Ovation made their first acoustic guitars with fiberglass backings. Other luthiers like Rainsong have been making acoustic guitars with all-synthetic bodies for a while now.

    Surely the Itako brothers are aware of this. So what are they doing that other luthiers haven’t already done? From this article, I’m afraid it’s not clear.

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  4. 4. Lionel 4:36 pm 09/6/2012

    It is interesting to see new results that contradict those of the early experiments of Antonio de Torres Jurado, the man who developped the modern classical guitar. Torres had discovered that only the guitar top had an influence on the sound and had proved it by building a guitar with a cardboard body

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  5. 5. Just_Jim 2:37 pm 09/9/2012

    This is hardly a “scientific” effort. The top wood is over 90% of the tone. When they found that a smaller body depth (68mm) “sounded better”, they had only discovered that with less body depth, the tone of the top wood was allowed to contribute more to the overall timbre. Greater body depth means later reflection from the back and sides, which reinforces different areas in the spectrum due to phase differences. Also, a greater cavity volume in the body lends “punch” and “bloom” (like a sort of reverberation in the low mids), which can enhance different formants.
    Measuring harmonics with an oscilloscope is unrevealing. As an example, think of a Stradivarius violin. Paul Reed Smith once told me that he examined 2 Strads in the Smithsonian. Not only were they made of the same wood, they were made from the same tree. Turns out that before that wood was harvested, Europe had experienced a “mini Ice Age”. So the wood itself had a different density, a different specific gravity, and a different strength-to-weight ratio because the climate had affected the speed of growth of those Alpine spruce trees.
    Good tone is all about the wood, and these guys are probably barking up the wrong trees.

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  6. 6. ecstatist 6:05 pm 09/9/2012

    The very best and most admired high fidelity sound equipment experts, wine and food tasters, art critics, extra sensory perceivers etc have all failed so impressively and consistently when tested in environments that have been double blinded that they refuse to undergo these tests anymore.
    These super extra sentient pseudophiles and naked emperors could probably become even more credible after undergoing some homeopathic treatments.

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  7. 7. yavuzhan 7:22 am 10/5/2012

    very, very nice …

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