Behind Stradivari's secret

It is a particular balance of timbre that makes the Stradivarius unique instruments. This particular feature was brought into focus by a multidisciplinary team coordinated by the CNR who conducted an experiment in which 70 luthiers were involved to evaluate the sonic qualities of four violins, including a Stradivarius.

The results, published in The Journal of the Acoustical Society of America, suggest that what makes the Stradivarius the preferred sound is a particular balance in the properties of the instrument's timbre. The experiment conceived by Carlo Andrea Rozzi of the CNR Nanoscience Institute (Cnr-Nano), Alessandro Voltini of the International School of Violin Making "A. Stradivari" of Cremona, Fabio Antonacci of the Polytechnic of Milan, Massimo Nucci and Massimo Grassi of the Department of General Psychology of the University of Padua (UniPadova) helps to clarify this apparent paradox.

The researchers invited 70 Cremonese luthiers to analyze and compare the sound timbre of four violins - two modern, one factory, and one Stradivarius - compared to the sound of a reference Stradivarius violin. Based solely on listening to five notes, the listeners showed a marked preference for a particular violin, in this case the Stradivarius. The researchers then identified a kind of 'signature' that distinguishes the preferred violin sound from those considered less pleasant. "Thanks to an in-depth analysis of the descriptions provided by the listeners and to vibro-acoustic measurements carried out on the instruments we were able to describe the preferred sound as having a particular balance of 'openness', 'clarity' and 'nasality'", explains Carlo Andrea Rozzi of Cnr-Nano, first author of the study.

The experiment was conducted in the name of excellence: thanks to the availability of the Municipality of Cremona, the researchers had access to violins from the Historical collection of the Cremona Violin Museum and the excellent acoustics of the Auditorium room for listening tests. . "The large and attentive participation of master luthiers and students of the International School of Lutherie has allowed us to obtain very reliable data", concludes Rozzi.