Published online 2 October 2008 | Nature | doi:10.1038/news.2008.1147


Old violins reveal their secrets

Acoustic measurements identify the signature of a Stradivarius.

violinsThe richness of a Stradivarius is apparent in its lowest octave.Punchstock

Why do the violins made by Stradivari and Guarneri del Gesù sound so good? Countless theories have been proposed for the secret of these eighteenth-century Italian instrument-makers, but attempts to identify a unique acoustic signature have proved fruitless. Now a study has finally identified a measurable sound quality that distinguishes these old violins from cheap, factory-made instruments.

After spending ten years painstakingly measuring the acoustics of violins rated from "bad" to "excellent" by professional musicians, George Bissinger of East Carolina University in Greenville, North Carolina, says that the 'excellent' old Italian violins in his sample show a significantly stronger acoustic response in the lower octaves than do the 'bad' violins, whereas those rated merely 'good' have intermediate values1. The high-quality tone is caused by a single mode of vibration of air inside the body, which radiates sound strongly through the violin's f-holes.

Violinists say there's no doubt that the immensely sought-after and expensive instruments are superior. "The sound differences are very real," says Ara Gregorian, the distinguished concert violinist who played the instruments for the tests. "Every violin has its own voice or tone."

“Violin-makers could actually use these results to help achieve a certain sound.”

George Bissinger
East Carolina University in Greenville, North Carolina

But it has long been a mystery where those prized tones comes from. New Jersey violin-maker Carleen Hutchins has been trying to crack the problem for half a century. "I think we can find out why great violins sound so good, learn their mechanisms, and use that knowledge to make consistently better instruments," she says. "There's no reason that music students should have to mortgage their futures to own a truly fine-sounding violin."

Yet many luthiers have been sceptical that science can say much about a violin's quality – despite suggestions that the great Cremonese craftsmen had a 'secret formula' for the varnish, or that the high quality was due to differences in wood density2 or special chemical treatments of the wood3. Typically, though, researchers have looked for distinguishing material features of the classic instruments, without testing whether these confer any quantifiable acoustic distinctions.

A big sound low down

Bissinger measured all manner of sound characteristics for the 17 instruments in his sample, which ranged from legendary instruments known as the 'Titian' and 'Willemotte' Stradivari and the 'Plowden' del Gesù, made respectively in 1715, 1734 and 1735, to mass-produced instruments for beginners.

He focused on the properties of the key vibrational resonances or 'modes' of the instruments, recording the frequencies of these modes, the radiativity (the sound radiated for a certain applied force to the strings at the bridge), the degree of focusing in specific directions (directivity), the flexibility of the wooden body plates, and the amount of damping of the sound. "The radiativity is closest to what the violinist hears and thus bears most directly on the quality perception," says Bissinger.

Almost all of these features showed no discernible trends from bad to good instruments. In fact, the two Stradivarius instruments showed respectively the highest and the lowest degrees of directivity in the sample.

But crucially, the best violins showed a more even radiation of sound across the range of acoustic frequencies that they generate. In particular, the greater strength of their lowest-octave response can partially account for the richness and sweetness of tone that violinists say they detect, says Bissinger. "They generally like a big sound low down," he says.

The Willemotte and Plowden instruments are owned by Mark Ptashne, an eminent molecular biologist at the Sloan-Kettering Institute in New York, and also an accomplished violinist. "Most really good players who play the Plowden say it is the greatest violin they have ever tried," he says.

When bad violins turn good

The alleged superiority of the best old Italian instruments is not necessarily all in the violin, however: Bissinger argues that, ultimately, a 'great' violin is created by a great violinist. He cites the case of the famous violinist Jascha Heifetz, who played a del Gesù. Heifetz was once approached by a fan after a concert, who complimented him on the "beautiful tone" his violin had had that night. Heifetz turned around, bent over, and put his ear close to the violin lying in its case and said, "I don't hear anything".

Yet Bissinger's studies suggest that the instruments themselves do matter. Even some 'bad' instruments can be made into 'good' ones by paying close attention to some basic details of construction and set-up, he says4. "Even a 'bad' violin somehow contains the essence of good violin sound, needing only the proper driving force at the bridge to elicit its capabilities."

"Violin-makers could actually use these results to help achieve a certain sound," he says. "There could be a much larger number of exceptional violins than there are." 

  • References

    1. Bissinger, G. J. Acoust. Soc. Am. 124, 1764-1773 (2008). | Article |
    2. Nagyvary, J. et al. Nature 444, 565 (2006). | Article | PubMed | ChemPort |
    3. Stoel, B. C. & Borman, T. M. PloS One 3, e2554 (2008). | Article | PubMed | ChemPort |
    4. Bissinger, G. J. Acoust. Soc. Am., submitted.
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