London, June 17 : Violins made out of rotten wood produce a more fresh and smoother sound, according to Swiss researchers.
A dose of rot made the wood less dense, and the researchers believe that a similar effect to the cold climate must have given legendary luthier Antonio Stradivari's instruments their distinguished tone.
The team is developing six violins, three from the wood treated with fungal infections and three with untreated wood.
The violins will then be played to experts in a blind test. They are expected to finish by the end of this year.
Sound usually travels more slowly through rotten wood. However, Francis Schwarze, at the Swiss Federal Laboratories for Materials Testing and Research in St Gallen, found that a few species of fungi infect wood without causing this slowdown.
The fungi degraded cell walls, but not the lignin tissue that makes wood woody.
And a chance encounter with a luthier made him realise that the characteristic could be beneficial for instrument makers.
For further study, team led by Schwarze incubated samples of Norwegian spruce, used for making the top plate of violins and infected it with fungus Physiporinus vitrius.
They also incubated the samples of sycamore tree, used for making instruments' bottom and infected it with fungus Xylaria longipes.
After 20 weeks of incubation, they found that the wood had reduced in density by more than 10 pct, simultaneously increasing the sound transmission, without weakening the structure.
"The longer the incubation period, the more the acoustic properties improved," Nature quoted Schwarze, as saying.
The fungally treated wood also produced a mellower timbre.
"I think they will have a smoother sound," said Martin Schleske, the Munich-based instrument maker who is collaborating with Schwarze. And treated wood looks better, he adds. "It has more of a golden colour, like a nice Italian instrument."
"It's a very interesting method, but it's only a first step," said Joseph Nagyvary, a chemist and luthier based in College Station, Texas.
The study appears in New Phytologist 1.