Sinfonia ai funghi
Do violins made of wood that had been treated with fungi sound the same as a fine, antique instrument? Acoustics experts at Empa are currently studying the body and soul of instruments made of “mycowood”. Precision structure-borne sound measurements and psycho-acoustic tests with volunteers should reveal whether a fungal treatment can really improve an instrument.
Exactly why certain violins, such as a Stradivarius, sound so special remains a mystery. Global warming is one explanation, says Francis Schwarze from Empa’s Applied Wood Materials lab in St. Gallen. “Nowadays, trees grow more rapidly and unevenly than during a very particular cold spell in the 17th century, when the wood for Stradivari’s instruments was felled,” explains the wood re-searcher. Apparently, today’s timber has less favorable properties for violin-making.
And so Schwarze set out in search of a way to modify wood to resemble its antique counterpart. He managed to recruit a helper from nature: a natural fungus that causes white rot in trees, which the researcher used it on the material under controlled conditions in the lab. Sure enough, the hyphae transformed the maple and pine wood into a material that is just the ticket for violin-making.
The white rot pathogens come from the sluggish brigade and eat appreciatively: for the two to three months, in which the germs feasted away on the timber for the biotech violins, they barely affected the wood’s mass. “Other pests break down up to 50% of the mass in the same time,” says Schwarze. The violin fungi, on the other hand, were content with 0.5 to 1%. All the same, the fungus eventually had to be stopped in its tracks. “As soon as the wood structure had reached the desired state, the fungi were removed using a germicidal gas.”
The mother of all violins
The goal was to manipulate the density of the wood, which is crucial for the sound, in such a way that the material is on a par with that used in the antique Italian instruments. Schwarze’s fungal treatment was modeled on a fine, antique violin by Guarneri del Gesù, the “Caspar Hauser” from 1724. Like his contemporary, Stradivari, Guarneri (1698 – 1744) made instruments in Cremona, Italy, which are highly coveted because of their special sound and played by great soloists today.
However, even the best material is no use if the craftsmanship is not up to scratch as well. Hence, master violin-makers produced exact geometric copies of the Guarneri violin using mycowood. Although music has always been a matter of taste, the acoustics researchers at Empa are interested in how a violin’s sound can be assessed objectively. The new project at Empa’s Laboratory for Acoustics/
Noise Control in Dübendorf is, therefore, studying the sound of the biotech violins from the very moment it is produced to the feeling it unleashes in its listeners.
A series of instruments, including the original, an untreated copy and various violins made of tonewood treated with fungi, are being tested. After all, the biotech instruments are supposed to demonstrate their capability according to scientific criteria.
The soul of a fungus violin
In the first step, Armin Zemp and Bart van Damme measure how the sound waves spread in the violin wood. As a musician’s individual bowing style might distort the results, an electromagnet stimulates the instrument’s strings for these structure-borne sound measurements. Moreover, the experiment is conducted in a special low-reflection lab, which does not cast the outgoing sound back onto the violin. In the meantime, a scanning laser doppler vibrometer records the vibrations of the material, measuring their frequency and amplitude at around 100 points on the violin’s body. “This will determine whether the waves spread differently in the wood,” says Zemp. “It will be particularly exciting to compare the mycowood violins with the original.”
After the violin’s body, however, its soul also needs to be measured: psychoacoustics experts are testing how people experience the sound of the biotech instruments. In the AuraLab for listening tests at Empa in Dübendorf, Beat Schäffer and Reto Pieren have been working with test subjects who have to evaluate audio samples of the instruments. Based on standardized questionnaires, the psychoacoustics experts are thus endeavoring to single out significant sound properties of the individual violins. “This will reveal whether we can establish a causal relationship between the wood structure, sound measurements and auditory sensation,” says Pieren.
The project was made possible by Walter Fischli, co-founder of the pharma company Actelion, whose foundation generously funded the development. A hobby violinist and trained scientist, Fischli shared the enthusiasm for research at the crossroads of music and biotechnology – yet another reason for the success of this long-standing cooperation.
Even in the run-up, the mycowood violins received plenty of praise. The first specimens have already competed successfully against a 1711 Stradivarius in a blind test in front of an audience. The musicians who were given the opportunity to play the biotech instruments included Oleg Kaskiv, a violin pro and professor at the International Menuhin Music Academy in Gstaad. Kaskiv is in-fatuated: “The mycowood violins have a warm, colorful sound that approximates the old Italian instruments.”
And although the instruments are still new and thus have not yet been played in sufficiently, it is already easier to tease sounds out of them an untreated violin is unable to produce. As concert halls are getting ever bigger, the musician finds the mycowood instruments with their powerful, carrying, warm sound particularly interesting. The current experiments will reveal whether the volunteers from the psychoacoustic tests are equally thrilled. //