Music Fridays – How Deep Is Your Guitar?
Posted by middlerage on October 26, 2012
From the “just so’s you know” files: A couple of Japanese scientists – who also happen to be guitarists, AND who also happen to be brothers – set out to determine what the perfect size of an acoustic guitar is. They report their findings in last month’s Scientific American. The article is gated but since I’m a subscriber, I’ll give you the gist. They constructed nearly identical guitars that varied only in the front to back dimension. The depths varied from 58mm to 98mm, and they both strummed and played the guitars while measuring the output sound with oscilloscope and whatnot. The goal was to find the depth with the richest, most beautiful, set of harmonics resonating out of the guitar. They also brought in 9 professional listeners (now there’s a job!) to give their opinion on the tonal quality. The result? 6 out of 9 professional listeners agree with laboratory devices that 68mm is the best sounding guitar depth. Up next, they plan to vary the center hole and perform new tests. We await their findings.
I’ll cut-n-paste the web page below:
The Physics of a “Just Right” Guitar [Preview]
A 68-millimeter-thick instrument produces the best-quality sound
By Evelyn Lamb
Image: GETTY IMAGES
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.
Tea Time With Jesse 
J. Notso Nieuwguyski said
Somewhere I have a thin book of Scientific American articles on musical instrument research. There was a similar article on optimizing the dimensions of orchestral strings. One thing the researchers discovered was that they couldn’t improve on the circa-1700 violin and viola designs of Stradivari and Guarneri. One other discovery was that if you made the body of a string bass big enough for maximum resonance, it’s too large to play.
…Not quite as big as the “octobass,” though:
middlerage said
well that’s just pretty darn cool. Cool but not pretty, errr, dulcet.
Dahveed said
When I was reading the article, I was thinking that the optimal depth has got to be dependent on the other body dimensions. (Maybe they said as much in the article, I dunno.) So that makes me wonder: when they start experimenting with the sound hole, are they going to find that it has a interdependent relationship with the body depth?
middlerage said
This is a very good point for which I don’t have an answer. It wasn’t mentioned in article.