One Saturday morning in 1994, retired engineer and violin acoustics researcher Oliver Rodgers parked his Ford pickup outside the renowned Philadelphia firm of William Moennig & Son. The shop was closed that day, but a violinmaker friend called Pamela Anderson had spoken about Rodgers with Moennig salesman Phillip Kass. Kass took an interest, came in on his day off, and proceeded to hand over a series of old Italian violins. “Here I am with this Stradivarius in my hand,” says Rodgers. “I walk out the door and across the sidewalk and climb into the back of my ten year old truck, where I test the violin. Then I wander back into the shop, and he hands me another.”
Rodgers, having realized sometime earlier that it would be easier to get his test equipment to a valuable old instrument than the other way around, had converted his truck into a mobile acoustics lab. He then began making house-calls, pulling up behind concert halls or in musicians’ driveways – and for two Saturdays, outside Moennig’s. The remarkable sound of the Strad he tested there – the “Havemeyer” of 1708 – became the benchmark against which he now measures all other violins.
Rodgers, Anderson, and I are eating lunch at Weia Teia, an excellent and surprisingly inexpensive restaurant in Oberlin, Ohio. It is day four of the VSA Oberlin Acoustics Workshop. Violinmakers occupy many of the tables, discussing everything from taptones to listening tests. Anderson is at the workshop for the third time as a participant. Rodgers has been on the faculty since the program’s inception in 2001. He is a past master at putting together functional equipment from materials at hand – discarded speakers, scraps of plywood, drinking straws – and at Oberlin this year he demonstrated a set of tiny hammers designed to excite specific violin body modes. Materials used: paperclips and pencil erasers.
Though a lot of sophisticated techniques have been used for measuring violin sound, Rodgers likes to keep things simple. The back of his truck is lined on the inside with strips of old carpet and foam to deaden the space acoustically. A microphone is connected to the sound card of an old computer. To measure an instrument, Rodgers simply plays an ascending glissando on each string. To maintain a predetermined position with respect to the microphone, he keeps the bridge in line with a piece of string dangling from the ceiling – and he always looks at the same point on the wall while playing. The computer records the glissandi, then charts the output of the instrument across its range.
Rodgers’s two-feet-on-the-ground practicality, along with unusual patience and a remarkable ability to explain complex acoustical phenomena in simple language, has led many violinmakers to claim him as a mentor. I met him in 1986 and soon realized that he was the one to go to when I didn’t know what the physicists were talking about. He helped me understand the engineering principals behind plate tuning, bridges, and bassbars. Having worked in the pulp and paper industry, he also explained a lot about the structure and chemistry of wood. At Oberlin two years ago, violin-maker Oded Kishony turned to him for help in developing what Kishony calls “string reciprocity” – an ingenious method for finding the vibrational modes of an instrument using “absolutely no tools,” as Kishony likes to say. “Oded gives me a half-hour call every 2 or 3 months,” says Rodgers. “Sometimes he has something really crazy on his mind, sometimes he is right on.”
Violinmaker Sam Zygmuntowicz joined the Acoustics Workshop faculty in 2003 and began developing a technique for quickly modifying the sound of a test violin nick-named “Gluey” – strips of poplar veneer are adhered to (and easily removed from) the outside of the instrument using melted rosin. One evening he and a team of participants were trying to figure out where to put the next strip, when Rodgers came by. “I asked Sam to play,” says Rodgers, “then I started to feel the violin top with my fingertips to see where it tickled most. When I suggested he put a strip at a certain place, it ended up working better than any of the guessing they’d done so far. Sam wanted to know how come I could do that. I got to bed rather late that night.”
Zygmuntowicz recalls that Rodgers had them put a couple of tiny stiffening strips near the treble f-hole. “It blew me away,” he says. “It was as though Oliver had pushed a button. You could hear the intensification of the sound. His approach is so tactile, so physical. It made me realize that acoustics is not just science – it is also an art, a craft.” Zygmuntowicz later visited Rodgers at home in Kennett Square, Pennsylvania, and he has since built himself a classic piece of Rodgers-designed test equipment, the “nodal line seeker”.
Rodgers’s closest and most longstanding working relationship is with Pamela Anderson. It began in 1990, when Rodgers realized he would need a trained violinmaker in order to do the experiments that most interested him. “I live in a retirement community,” says Rodgers. “I mentioned at lunch one day that I was looking for a violinmaker open-minded enough to do some things no violinmaker ever did.” Someone mentioned Anderson, who had worked at Moennig & Son. “That interested me because I’ve known Moennig for 50 years or so. My instruments came from there; my children’s instruments came from there.”
Rodgers visited Anderson at home and set up some test apparatus on her kitchen table. “I asked if she would be willing to modify an instrument – to really sacrifice it – and she said yes.” And so began a long series of “what-ifs.” What if the soundpost side of the back were stiffer, or the top in the area of the chinrest? To test this they stuck thin strips of wood to the outside of the instrument – much as Zygmuntowicz does now.
Anderson majored in philosophy at Bryn Mawr, but she grew up playing cello, and while at college she took lessons with Philadelphia Orchestra cellist Francis de Pasquale. After graduating cum laude, she went to violin-making school in Cremona. Back in America, she landed a job with Moennig. “Violin-makers are conservative by training,” says Anderson. “There are precedents for everything. Working with Oliver has given me confidence to try things – and even go too far sometimes.”
One of the first things they tried involved her own cello. Says Rodgers, “We got some putty and put it on her bassbar – saw what it did here, what it did there.” The cello would only just fit into the truck, and the software wouldn’t handle the bottom octave. Still, they got some very interesting data, and when violinmaker David Rivinius later came by with one of his asymmetrical violas, they ended up adding extra mass to the bassbar in the form of a paperclip. Rivinius liked the results well enough to remove the back of the viola and replace the paperclip with a piece of ebony of equal mass.
Both Rodgers and Anderson have well-trained ears, but Anderson is gifted with a rare perceptual ability known as synesthesia. She experiences sounds as images, rich in color and texture. These images are not random, for the same sound will always produce the same image. What is more, she can remember the images accurately enough to usefully compare remembered sounds with present ones. Rodgers gives an example: “Someone came into Moennig’s with a cello. It was supposedly very valuable but had somehow lost its sound and wouldn’t sell.” The cello had been thoroughly checked at an earlier time, and was found to be in order. When it came back again, Anderson heard it played from the next room. Says Rodgers, “The sound reminded her of a cello we had tested with a weight at a certain place on the bassbar.” So Anderson modified the cello’s bassbar accordingly. The sound improved and it sold soon afterward. “All that came from blob of putty,” says Rodgers. “And Pam’s memory.”
At 87, Rodgers is tall, slender, and soft-spoken, with a modesty and graciousness that seem of another time. He was born and raised in the copper-smelting town of Anaconda, Montana, during the depths of the depression. This he sees as inadvertently fortunate, for the smelting company, hoping to keep laid-off workers from leaving the area, put money into the town’s schools. They hired Charlie Cutts – a professional pianist who had turned to teaching after losing some fingers during World War I. Cutts convinced other veterans in the town to put some of the money intended for a war monument into musical instruments for the high school. And so the Anaconda Soldiers’ Memorial Band was formed. “I took out every single instrument and played it some,” says Rodgers. He went on to play baritone in the band, and eventually won first prize as baritone soloist in a statewide competition.
Rodgers took up viola mainly to fill an empty chair in the family string quartet. He soon became fascinated by how no two violas sound alike – a fascination that remains undiminished to this day. And he still plays string quartets, often with his son on the cello. Though Rodgers went to Harvard intending to become a music teacher, he found he disliked the academic approach to music, and so switched to engineering – another long-time interest. He eventually specialized in vibration engineering. His first job was at Westinghouse, where he spent several years tracking down the unwanted vibrations that were causing the blades to fall off new steam turbines.
Rodgers retired from engineering in 1980 – and soon began what would become a long and productive second career in violin acoustics. He called researcher Carleen Hutchins about attending monthly meetings of the Catgut Acoustical Society. She said yes – but only if he brought something to work on. Says Rodgers, “Almost immediately I realized that some of the engineering things I knew could be useful for plate tuning. The practice then was that if you didn’t know what to do next with a plate, you took it to Carleen, who told you where to scrape off wood. It was fairly clear to me that she was guessing, and that I could help systematize the process using finite element analysis.”
Finite element analysis is a method for modeling an object on a computer in order to predict how modifications to the object will change its vibrational behavior. It requires computing power of a magnitude that was not readily available then, so Rodgers set off in search of a suitable machine. He ended up the University of Delaware’s new vibration lab. “I was an adjunct professor,” he says. “No duties except working with students. No pay, but the run of the place. I stayed for 12 years.”
Rodgers focused first on free plates – on how their taptones change when wood is removed at various places. Then came studies of bridges, sound posts, bassbars, and eventually, whole instrument bodies. His more than twenty papers (published mainly in the CAS Journal) are practical in nature and written in relatively non-technical language. They remain an invaluable resource for violinmakers wishing to incorporate acoustical know-how into their workshop practice.
Though Rodgers has learned a great deal about how violins work, he is refreshingly unwilling to generalize about them. “They are all different,” he says. “What works for one may not work for another. You need to poke around.” That said, Rodgers has identified at least two characteristics shared by the best old instruments – and these characteristics were highlighted when he measured twelve award-winning violins at the 2004 Violin Society of America competition in Portland, Oregon. In a paper on the subject (VSA Papers, Summer 2005, Volume 1, No.1) he compares the sound output of award winners with that of the ‘Havemeyer’ Strad. In the low frequency range, none of the new instruments have a Helmholtz (or ‘A0’ ) resonance that can compare with the Strad’s in terms of sheer amplitude.
Rodgers found that the new instruments all had strong peaks in the high frequency region responsible for brilliance and projection. Furthermore, the ones with “many closely spaced [peaks] in the upper frequency region seem to have been favored by the judges.” Still, none of them could match the virtually unbroken range of peaks produced by the Strad. Though researchers have often noted the importance of high output in this frequency region, Rodgers, to the best of my knowledge, is the first to point out that a continuous response right across the region is important. “If it’s splotchy up there, you can hear it.” he says.
It is one thing to read pronouncements about what new instruments can and cannot do. It is quite another to have your own violin measured in a way that makes visible its strengths and weaknesses. Early in the Oberlin session, Rodgers posted a sign-up sheet for makers who wanted their instruments tested. As a result, he has spent most of his free time in the back of the truck – which is where he is headed after lunch. As we get ready to leave the restaurant, I ask Rodgers what he thinks the response curve of a perfect violin would look like. He responds without hesitation, “Just like the Havemeyer.” When I ask what he and Anderson plan to work on next, he says, “We have some loose ends to tie up.” Then he smiles. “One loose end leads to another.”