Can a computer software program help create the next Stradivarius violin? That’s the hope of researchers at the Massachusetts Institute of Technology (MIT) who have taken a small step in that direction with the first physics-based computational model that can simulate the sound of a violin.
The MIT virtual violin project builds on the 2006 work of scientists who made a CT scan of a 1715 “Golden Age” Stradivarius that produced 600 “slices” or 3D views of the violin. MIT researchers took these publicly available CT scans and divided each scan into millions of tiny cubes they labeled “elements.” For each element, the researchers applied physics-based equations relating to stress and motion to predict how each material element would move in relation to every other element across the instrument. Among the details noted were whether the violin’s back plate was made from spruce or maple and whether a string was made from steel or natural fiber.
Lastly, a similar process was carried out for the air surrounding the violin. The researchers divided approximately one cubic-meter volume of air and then applied acoustic wave equations to predict how each tiny parcel of air would move and contribute to generating sound. The end result was a matrix of millions of individual elements interacting with each other.
So how do you recreate the pluck of a violin string in a virtual model? The researchers simulated a simple string pluck by directing one of the virtual violin’s strings to stretch out and then rebound. For notes that required pressing down on a violin’s fingerboard, the researchers added a condition in which the string is held fixed in the section of the fingerboard where a violinist’s finger would press down. Using this technique, the researchers were able to pluck out several notes in “Daisy Bell” and “Bach’s Fugue in G Minor.”
While MIT’s virtual violin isn’t quite ready to take its place in an orchestra pit, the researchers believe it can help luthiers test how a violin might sound when certain dimensions or properties are changed, such as the thickness of the violin’s back plate or the substitution of wood types. The virtual violin could shorten a design process that is lengthy and costly, say the MIT researchers. With that in mind, the MIT researchers hope to virtually mimic the more complex bowing style of playing and the more complicated nuances of sound produced by human musicians going forward.
A remaining mystery is why a centuries-old Stradivarius violin sounds so great in the first place. Experts cite a range of possible explanations including materials, period chemicals and the instrument’s design proportions. For example, one contributing factor may be that a Stradivarius violin was made during a mini ice age period characterized by slower-growth trees that yielded denser wood with better acoustic properties. Creating a virtual Stradivarius may prove to be as complex and mysterious as the instrument itself.
