Researchers use X-ray and CAT scans to reveal the secrets of golden age violins

A team of MIT acousticians and fluid dynamicists have teamed up with Bostonian violin makers to meticulously analyze hundreds of instruments from the Cremonese period, considered the golden age of violin making. The findings not only reveal key design features, but also shed light on whether the development of the instruments was deliberate, or simply a product of human error.

The study focused on violins from premier Italian workshops of Amati, Stradivari and Guarneri, with the team analyzing measurements from hundreds of 17-18th century instruments. They made use of X-rays and CAT scans, as well as technical drawings acquired from museums, collectors and databases, comparing dimensions and measurements of acoustic resonances.

The study identified the shape and length of a violin’s f-holes – the contoured openings through which air escapes – as a key feature affecting the power, or fullness of the produced sound. Specifically, it was found that most of the sound produced flows through the hole’s perimeter rather than its interior, meaning that the more elongated the sound hole, the more powerful a sound the violin can produce.

The thickness of the backplate was also found to have a significant impact on acoustic power. The elasticity of the wooden constructions allows for minutely expansion and contraction in response to air vibrations. The study found that the thicker an instrument’s backplate, the more it boosts the violin’s sound.

The researchers also revealed secrets about the development of the instruments, finding that back plates thickened and f-holes elongated as time went on. The team fed the recorded measurements into an evolutionary model, the results of which showed the changes to be one of natural mutation rather than a deliberate, conscious development.

In other words, changes in 17-18th century violin design can, in all likelihood, be attributed to repeated craftsman error. However, that doesn’t necessarily mean that they weren’t listening carefully to the violins they were constructing.

"People had to be listening, and had to be picking things that were more efficient, and were making good selection of what instrument to replicate," said Nicholas Makris, a professor of mechanical and ocean engineering at MIT. "Whether they understood 'Oh, we need to make [the sound hole] more slender', we can’t say. But they definitely knew what was a better instrument to replicate."

The study, led by Prof. Makris, forms part of an extended examination of the acoustic dynamics of stringed instruments. The team believes that the results may be useful for modern violin makers looking to design instruments capable of producing a full, powerful sound.

Source: MIT