Kazutaka Itako, an electrical engineer at the Kanagawa Institute of Technology in Japan, has played the guitar since he was six years old. Satoshi Itako, who has a master’s degree in electrical engineering, works as a guitar fabricator. Together the brothers have been investigating the optimal shape for guitars. Experts have settled many questions relating to the best shape for violins, but far less research has been done on guitars. The Itakos’ preliminary work, presented in May at the Acoustics 2012 conference in Hong Kong, looks at one variable: guitar depth. They crafted four nearly identical instruments, ranging from 58 to 98 millimeters deep. The Itako brothers tested the tonal quality and harmonics of four guitars, while a performer played open strings with two different strumming styles, using both objective and subjective measures. With an oscilloscope, they measured the harmonics, integral multiples of a fundamental tone. (A pure wave has only one frequency, yet it sounds sterile and artificial. The more harmonics, the richer the sound quality.) In addition, nine musically trained listeners evaluated the guitars. The 68-mm-thick guitar included the richest combination of harmonics, and six of the nine listeners rated it as having the best tone quality. The Itakos are now moving on to the question of how the size of the sound hole alters the guitar’s tone. After that, they plan to determine whether a synthetic material, such as fiberglass, could make instruments that are just as sonorous as wood versions, which are time-consuming and finicky to make. The Itakos’ goal is to identify ideal dimensions and materials for a high-quality subprofessional instrument, which would allow more amateur strummers to buy good guitars at affordable prices. COMMENT AT ScientificAmerican.com/oct2012
Experts have settled many questions relating to the best shape for violins, but far less research has been done on guitars. The Itakos’ preliminary work, presented in May at the Acoustics 2012 conference in Hong Kong, looks at one variable: guitar depth. They crafted four nearly identical instruments, ranging from 58 to 98 millimeters deep.
The Itako brothers tested the tonal quality and harmonics of four guitars, while a performer played open strings with two different strumming styles, using both objective and subjective measures. With an oscilloscope, they measured the harmonics, integral multiples of a fundamental tone. (A pure wave has only one frequency, yet it sounds sterile and artificial. The more harmonics, the richer the sound quality.) In addition, nine musically trained listeners evaluated the guitars.
The 68-mm-thick guitar included the richest combination of harmonics, and six of the nine listeners rated it as having the best tone quality. The Itakos are now moving on to the question of how the size of the sound hole alters the guitar’s tone. After that, they plan to determine whether a synthetic material, such as fiberglass, could make instruments that are just as sonorous as wood versions, which are time-consuming and finicky to make. The Itakos’ goal is to identify ideal dimensions and materials for a high-quality subprofessional instrument, which would allow more amateur strummers to buy good guitars at affordable prices.
COMMENT AT ScientificAmerican.com/oct2012
