Three Violins of Cremona - Form, Sound, & Motion
Titian Stradivari 1715, Plowden Guarneri 1735, Willemotte Stradivari 1734
Recent years have seen an explosion in the information available on fine violins, with high quality photographs, measurements and description now commonplace. This wealth of archival information has played a large part in the blossoming of contemporary violinmaking. However, the most important aspects of the violin are those that we cannot see – the actual vibrations that create the sounds that we hear, and the intimate interaction between player and instrument, bow and string.
The Testing Sessions
With this study we are now able to see the first true 3-dimensional animations of a violin's vibrations – what a Strad does, not only what it looks like! Traditional violin documentation is included, with technical measurements, thickness mapping, and photographs.
This project began at the Oberlin Violin Acoustics Workshop, when I joined the faculty and met Dr. George Bissinger, a longtime leader in violin acoustics research. He had one of the world's best acoustics research labs, but little access to truly great violins. We had to get some good fiddles to his lab! The leading maker of vibrometry lasers agreed to bring their most advanced 3d scanning laser – if Dr. Bissinger could obtain a suitable Strad to scan. The stage was set.
For this opportunity the staff of the VSA Oberlin Acoustics Workshop rallied to find a suitable Strad and arrange the complicated logistics. Due to acts of great trust and generosity, I was able to borrow the 1715 "Titian" Stradivarius (thanks to Cho-Liang Lin and the Miller family), and both the 1735 "Plowden" Guarneri del Gesu and the 1732 "Willemotte" Stradivari (courtesy of Dr. Mark Ptashne). Twelve million dollars of liability insurance was obtained with the help of Ellis Hershman of Heritage Insurance and the support of the VSA and the CAS Forum.
Finally our team of Fan-Chia Tao, Joseph Curtin, Joe Regh and I made our way to Dr. Bissinger's Acoustics Laboratory at East Carolina University, Strads and Guarneri in tow. The instruments were carefully suspended on a testing apparatus and repeatedly tapped on the bridge with a calibrated impact hammer, while the three laser cameras scanned from point to point. The sound radiation was later recorded in an anechoic chamber. In addition, the violins underwent CT scans to determine their density and shape properties.
Using a calibrated and measured input, and acoustic scans to measure sound output, Bissinger has begun to calculate "radiation efficiencies" and "damping" characteristics for these violins. Damping and sound radiation are all influenced by wood choice, varnish and age, and it is here that the "Old Cremonese Sound" may reside. This is a final frontier in acoustic research.
The Violinmaker's Perspective: The methods and goals of pure research, which value repeatable and verifiable results, are often beyond the practical interests of violinmakers. On the other hand, scientists don't need to actually make any violins. For us, we can draw an immediate value in an enhanced understanding of the behavior of the violin – a more informed intuition. The tools of technology are helping us move beyond the view of the violin as an unchanging artifact, to form a dynamic acoustical vision of the violin.
A first step in an acoustical view is to become aware of the complex harmonic content of every note on the violin, and how that changing balance of frequencies defines the timbre of the sound ("Spectral Analysis"). Next is to begin to visualize the violin in motion. Any instrument has a different type of motion or "mode" for each frequency, but in real use vibrates in many different ways simultaneously, to create the mix of frequencies that comprise any note. "Modal Analysis" breaks down this complex mix of motions frequency by frequency, to create "maps" of mode behavior. This is where the 3d animations are so compelling. Using the laser scan data, the software creates individual mode animation, exaggerated but comprehensible. Seeing the hidden motions of the violin is also extraordinarily beautiful.
A number of researchers have introduced these concepts to the violinmaking community, including Norman Pickering, Oliver Rodgers, and Martin Schleske. However, these new imaging tools are so vivid that a violinmaker without scientific training can begin to absorb this vision in an intuitive way.
Looking at the 3d animations yields continual insight and speculation about the basic design of the violin: "Oh, that's what the corner-blocks are for; that's what the sound post does; that's why the f-holes are shaped like that; that's why the arch has those shapes; that's what the bass bar is doing; that's why the ribs are thin; that's why the back is thick in the center," and on and on.
There is still a long leap to being able to fully control those variables, but the clear implication is that all these design aspects of the violin could be used with real purpose and intention: change the structure, change the vibration patterns, change the frequency mix, change the tone. It indicates how malleable the sound and structure of a violin truly can be, and suggests possible strategies for shaping sound. We now have increased access to a dynamic vision of the violin, as what Schleske calls a "resonance sculpture" rather than a complicated carpentry project.
It is our hope that this scientific research can be combined with traditional violin expertise to produce a more comprehensive understanding of the great violins, and of the hidden inner workings of our craft.