Stradivari’s Rainbow

Stradivari’s Rainbow  —  07/10/14

Photo by Kim Pardi courtesy WikiCommons

Photo by Kim Pardi courtesy WikiCommons

In 1704, the year that Stradivari built the violin now known as the “Betts,” Isaac Newton published his second book, Opticks. In it he explains the refraction of white light into its component colors by a prism. A century later, Keats famously lamented Newton’s explanation, which to his mind drained the beauty and mystery from the rainbow. In the poem “Lamia” he wrote, “Do not all charms fly at the mere touch of cold Philosophy?”

I suspect most people today can find charm in a rainbow, all the while knowing it can be explained scientifically. Still, the underlying worry that scientific knowledge comes at a cost to our aesthetic or spiritual life lives on, and perhaps nowhere more than in the violin world. The science of the violin has lagged far behind that of the rainbow, in good part because the technology needed to accurately measure sound and vibration was not developed until the 20th Century. By then Stradivari had become a kind of figurehead for the persistence of mystery in an age of analysis.

As a young violin-maker, I thought of violin science with suspicion, even hostility. Though I had been devoted to science as a child, in my teens I fell in love with the violin, and with it the worlds of art and literature. By the time I took up making, I was a failed violinist and violist, but still needed to think of myself as an artist, as someone who relies on intuition and a sense of beauty more than “cold philosophy” to find a way forward. Mine would be the path of the poet, the painter, the dreamer. At a Violin Society of America meeting in the early 1980s, I attended a lecture entitled “What Researchers Can Do for Violin-makers.” As the speaker stepped up to the podium, I turned to a fellow maker and said, “What they can do is quit!” And I meant it. I didn’t want scientists poking around in my art.

I was hardly alone in feeling this. Here is violin-maker James McKean in his recent memoir “Art’s Cello,” explaining why he never weighed the tops or backs of his instruments: “I knew that all the lab-coat violin-makers did. It was the kind of thing they loved – hard numbers they could compare. Graphs, charts, printouts, and oscilloscopes. I found all that kind of thing worse than useless. It distracted from the most important measurement of all: what your hands tell you.”

The man whose lecture I so objected to was Norman Pickering, a brilliant engineer, musician, inventor, string-designer, and researcher whom I later came to revere. Years after that particular lecture, I was chatting with him before a talk I was about to give on, yes, violin acoustics. After scanning the meager audience he said (as though preparing me for the utter lack of interest my talk would likely generate), “there’s a special kind of silence that comes at the end of an acoustics lecture.”

And so there was. It may have been due to a sense that, because the Old Italian makers didn’t know much about violin acoustics (nobody did back then), nor should we. If you want to make a Strad, you need to think like Stradivari, so best not clutter your mind with non-Stradivarian concepts.

Even top scientists said to be wary. When I interviewed Cambridge Professor Jim Woodhouse, a leading figure in violin research, he put it this way, “Scientific advice should come with a government health warning – may be harmful to your instrument! Science can be useful in sending you in the right direction, but if you follow some theory to the point where you start to think, ‘I don’t want to do this, but science says I must,’ then the science is probably wrong.”

Much of it was wrong. The violin has inspired super-sized portions of bad science, every morsel of which seems to make the headlines. A fair percentage also gets served up at violin-making conferences – or at least it used to, so there was every reason to think twice before applying the latest scientific theory to your next violin. Scientists work with hypotheses, which can later be revised. Violin-makers work with wood, and as the old saying goes, Twice cut and still too short.

The majority of violin-makers, at least those of my generation, were not scientifically inclined. We had instead, I believe, a yearning to recover whatever the Cremonese might have known about violin-making in the early 1700s. We were fascinated by ancient varnish formulas, esoteric wood treatment processes, arcane geometrical systems. These would not so much explain the mystery of Old Italian violins as allow us to partake in it. We would become Old Italian makers. We would pick up where the Cremonese left off, and a new Golden Age would begin.

In 1985, seven years after building my first instrument, I moved to Ann Arbor, where I met University of Michigan professor Gabriel Weinreich, a former Bell Labs physicist who had become one of the top experts on violin acoustics. Through conversations with him I discovered that virtually all my “intuitive” ideas about how the violin worked were wrong. Some ideas were metaphorically true, meaning they were literally false. Others were just plain wrong from any angle. My early resistance to violin science began to seem silly. No-one objects when scientists try to take the mystery out of cancer. Bad violin sound may not be life-threatening, but why object to research that could lead to a cure?

People don’t object, or not exactly. Instead, they say that science isn’t up to the task. You’ve read the newspapers: For centuries scientists have struggled in vain to unravel the mystery of Stradivari’s sound. You can always say, “that’s just the media,” but this kind of thinking has crept into the work of serious writers, thinkers, and historians. Tony Faber, in the Afterword to his generally excellent book “Stradivari’s Genius,” recounts a visit to Cremona’s town hall, where he hears someone play a 1715 Stradivari known as the ‘Cremonese.’ Reflecting upon this experience (and on past plans by its caretakers to subject the instrument to a battery of scientific tests) Faber writes “The Cremonese stands as a symbol of science’s failure to come to grips with the secrets of Stradivari.” He goes on to describe some of the technologies that have been used to study the violin (including x-ray diffraction and dendrochronology), and concludes that, “Little has been accomplished.”

The question becomes, I suppose: what constitutes an accomplishment? High on the list (at least in the public mind) would be the discovery of some physical reason why Old Italian violins sound better than other violins (assuming that they do). Violin-makers would naturally appreciate clear-cut recipes for building instruments that sound like the best Old Italians. Scientists, however, define success largely in terms of doing good science.

Doing good science inevitably involves publishing papers in peer-reviewed journals. Compared with larger, better-funded fields such as optics or particle physics, the number of violin-related papers in the literature is vanishingly small. Few of the important papers have made the headlines, probably because they can’t be spun to solve the riddle of Old Italian sound. No one ever opened the morning news to read Helmholtz Discovers Traveling Kinks in Bowed String, or Schelleng Creates Minimum Bow Force Diagram, or Weinreich Proposes Sound Hole Sum Rule, or Woodhouse Relates Playability to Bridge Admittance.

Scientists may be drawn to the violin by its mystique, but once in the field, they tend to work on problems that are not easy for violin-makers or players to understand and therefore care about. As Weinreich likes to say, “Scientists are interested in scientific questions. If the answers are helpful to violin-makers, then that is gravy.”

Over the past several centuries, many distinguished scientists have taken an interest in the violin. Has their work been in vain? By any reasonable accounting, the answer must be no, for we now have a remarkably detailed understanding of how the instrument works at a basic physical level. While there is still much to be learned, I hope to show in upcoming posts that violin science has reached a point where it is directly useful to both makers and players.

Photo by Kim Pardi, courtesy Wikimedia Commons

 

Violins & Voices (part 2)  —  05/22/14

KONICA MINOLTA DIGITAL CAMERA

A few years ago a client of mine from the Pittsburgh Symphony Orchestra came in for an adjustment and asked about a prototype electric violin she saw sitting on a cabinet. I told her about the Digital Violin, then went to my computer and played back a sample recording made on it. It was the opening solo from the Tchaikovsky Violin Concerto played, I told her, “by a good violinist.”

I had done the demo often – playing first the raw output from the instrument, then the same thing filtered through an electronic emulation of Guarneri del Gesu violin. If you’ve ever listened to the unmodified sound of a solid-body electric violin, then you know the buzzing, colorless sound it produces. And yet a few seconds into the “raw” version of the Tchaikovsky, my client said, “Is that Ilya Kaler?” When I asked how on earth she knew, she answered immediately: “The sound.”

The sound? It barely sounded like a violin, let alone the one I built for Kaler – but then I remembered that he had been guest concertmaster with her orchestra the previous year. Clearly, she had recognized not his sound so much as his playing gestures – all the technical and musical inflections that add up to a recognizable “voice.”

A great violinist once told me that violinists all sound alike these days. In the old days, he said, you could immediately recognize the sounds of artists like Heifetz, Kreisler, Elman, and Menuhin. This is complaint commonly voiced by players and critics alike. Out of curiosity I asked if he thought he could, while blind-folded, tell which of his students were playing at a masterclass. “Yes, of course,” he said. It is tempting to conclude that violinists are better at telling each other apart than they sometimes pretend to be. But in fairness, I am probably taking the complaint too literally. What was meant is that, while there are a great many accomplished violinists in the world today, there are very few distinctly original voices.

The last post raised the question of why we find it easy to tell each other apart by our speaking voices, but rather difficult to tell violins apart – at least in blind listening tests. “Old Italian sound” does not seem to be something we recognize in the way we recognize, for example, an Irish accent. Why not?

An obvious difference between the violin and the voice, is that with the latter, “player” and “instrument” are completely integrated. You can’t take Clinton’s vocal apparatus and ask Obama to make a speech with it. On the other hand, a gifted mimic can use his own vocal apparatus to imitate both presidents well enough that you would at very least know which was which. This suggests that, broadly speaking, we recognize each others’ voices more by the way we use them than by their innate tonal characteristics.

A violin can of course be used by any player. Ask Pinchas Zukerman to play Itzhak Perlman’s violin, and most people will agree that he sounds pretty much as he always does. While it is possible to imagine Zukerman using his own Guarneri del Gesu to imitate Perlman’s playing, it is harder to imagine him using it to imitate Perlman’s Stradivari. What would that even mean? All this suggests that the recognizable attributes of violin sound are more related to how the player uses an instrument, than to the instrument’s innate tonal characteristics.

Most musical instruments can be looked at in terms of two separate systems, an “oscillator” and a “resonator.”  The oscillator provides a signal that varies in pitch and amplitude more than in timbre. This signal is then “colored” by the resonator. The bowed-string and the vocal chords both act as oscillators, while the violin body and the various resonating chambers in the vocal apparatus (lungs, throat, sinuses, mouth) act as resonant amplifiers.

There is, however, an enormous difference between the vocal tract and the violin body. People can freely modify the placement of their vocal resonances – and do so with every change in vowel. A violin is made with wood, not flesh, and so it resonances, or “modes of vibration” are relatively fixed. In this it more resembles a room than the human voice.

A room’s acoustical characteristics are entirely determined by its modes of vibration. These can be modified only by physically changing the room – for example by rearranging the furniture or removing a carpet or opening a window. Similarly, a violin’s modes of vibration can be modified by moving the soundpost, trimming the bridge, and any number of other adjustments. Just as a single person changing position in a room will somewhat alter its acoustics, so changing the way you hold a violin will somewhat affect its acoustical behavior.

It is, however, the relative stability of the violin’s resonant structure while it is being played that is important here. Our perceptions are highly sensitive to changes, but tend to ignore or “tune out” things that remain constant. We notice the sound of a refrigerator mainly when it turns on or off. This happens not just with relatively simple background noises, but with highly complex acoustical constants, such as the acoustics of a room.

Physicist Gabriel Weinreich calls it the “culvert effect.” If you enter a highly resonant passageway while speaking with a friend, conversation may suddenly become unintelligible. Very soon, however, the brain seems to separate the fixed acoustics of the space from the highly dynamic, continually changing signals that make up spoken language. Conversation again becomes possible.

It is reasonable to assume that when listening to a violin, our auditory system focuses less on the unchanging acoustical characteristics of the violin body than on the continuously changing signal produced by the violinist (i.e., the music). If a player switches violins, the difference in sound may at first be noticeable – even dramatic. But the ear soon tunes-out the new acoustical constant, and focuses again on what the player is doing.

Just as the ear adapts itself to the acoustical environment, violinists adapt themselves to individual instruments. Good players soon find a way to project their own “voice” using almost any violin. There are, however, limits to what both players and listeners can accommodate. Not all rooms make good concert halls, and not all violins make effective musical tools. Just what makes a “good violin” is a question that has perplexed scientists for centuries. Recent research is providing some surprising answers, and these will be the subject of future posts.

 

Violins & Voices – Part 1  —  04/29/14

Detail of the "Leonora Jackson" Stradivari, 1714

Detail of the “Leonora Jackson” Stradivari, 1714

Players and makers often talk about differences in tonal character between Stradivari and Guarneri del Gesu violins. Here is Yehudi Menuhin on the subject:

. . . my Khevenhüller Strad delivers a sweeter tone than my Soil Strad yet does not quite match the Soil’s power to ring out above a symphony orchestra. Transcending such idiosyncrasies, however, is a generic temperament . . . which must, I feel, reflect the hand that carved them.

  . . . [Stradivari] made brilliant, burnished sound that conveys, for me at any rate, moral notions of loftiness. One must rise to a Strad before it will speak from its craftsman’s soul. It spurns the man who lets his hand exert too much pressure or his finger fall ever so slightly wide of its mark.  As master, there is ultimately no pleasing him except by faultless workmanship, for he shines upon one’s blemishes. As mistress, there is no winning her except by incessant victories over oneself, by demonstrations of perfect control.

. . . the Guarnerius, whose earthier voice belies the fact that it is often slightly smaller than most Strads, sings through its pores and sings de profundis. One need not rise above oneself, for it appeals to the natural man. Although Strads have been the dominant instrument of my life, at regular intervals I have played Guarneri; finding the first gold while the second brings to mind the red of Sainte-Chapelle stained glass.

 “Unfinished Journey,” pages 296-297

 Menuhin was a great violinist, an eloquent writer, and a highly cultivated man, so it is hard to imagine anyone better qualified to speak on this subject. It is not clear, however, how obvious the differences he describes might be to the rest of us. Should any interested listener expect to hear them by, for example, comparing recordings of Strad players like Menuhin, Milstein, and Oistrakh with those of Guarneri players like Heifetz, Stern, and Zukerman? Or can the differences be heard only by expert listeners, or by the players themselves?

The dull fact of the matter is that numerous listening tests have shown that even expert listeners have trouble telling nominally very different violins apart. Take for example a blind-test organized by BBC radio in the mid-1970s. Violinist Manoug Parikian stood behind a screen and played the opening of the Bruch Concerto and an excerpt from Bach’s Chaconne on each of four violins: a Stradivari, a Guarneri del Gesu, a Vuillaume, and a Ronald Praill that was barely a year old.

Isaac Stern, Pinchas Zukerman, and the British violin expert and dealer Charles Beare were each asked to guess which instrument was which. No-one correctly identified them all. Stern and Beare did best, getting two out of four correct. The Praill violin was mistaken for both the Strad and the Guarneri.

It goes without saying that a healthy skepticism should be reserved for test results that seem to disprove the existence of the actual. In this case, the panel (before giving their answers) spent some time pointing out the test’s deficiencies: The excerpts were too short and too limited in tonal possibilities; there was no chance to revisit each instrument for extended comparisons; the studio represented only one of many possible listening environments, and so forth.

It is true that the BBC test was not undertaken with sufficient rigor for the results to stand as scientific evidence. This does not mean there is nothing to be learned from it, or from other informal experiments. And yet, fairly or unfairly, listening tests have had little apparent effect on prevailing beliefs about violin sound. Rather than speculating about why this may be the case, I would like to consider a very general question: What kinds of sounds are humans good at recognizing and comparing – and are the sounds of individual violins among them?

As a point of reference, imagine three widely-familiar voices – those of U.S. presidents Clinton, Bush, and Obama. How clearly you can hear each of them in your mind’s ear probably depends on what kind of mind you have, and what kind of ear. Imagine however that you have been blindfolded and then, after listening to each president say the same simple phrase, are asked to identify which voice is which. Would you feel nervous?

Probably not. Humans and many other species are adept at recognizing each others voices. Bats, for example, can find their off-spring among millions of other baby bats, all crying out simultaneously in a light-less cave. Not only do we recognize the voices of people we know, we recognize general qualities in the voices of strangers – an Irish accent, for example, or the effects of a common cold.

The violin (or viola or cello) is often said to be the instrument closest to the human voice. Is it therefore reasonable to suppose that the sound of an individual violin is as distinctive and memorable as that of an individual human?

Well, imagine the sound of a Stradivari violin. What do you hear? Let’s  be more specific: imagine the sound of a particular Stradivari, the Soil of 1715. This was Yehudi Menuhin’s principal instrument; it is now played by Itzhak Perlman. Perhaps you can call to mind a passage from one of their recordings, or remember how the violin sounded in a live concert. But now imagine you have been blindfolded and asked to identify the Soil from a line-up of five other violins, having heard the same brief passage played on each. Would you feel nervous?

You should. Notwithstanding everything said and written about the differences between various kinds of violins – old, new, Italian, French, German, English – these differences have been surprisingly difficult to pin down. This does not mean that they don’t exist. Variations among individual instruments of the same type can be relatively large, while general differences between types may be quite small – meaning one would need to compare a very large number of violins in order to draw conclusions. It could also be that some kind of specialized perceptual training is needed to facilitate discrimination between instruments. Consider, for example, that tiny differences between bird-calls may be obvious to ornithologists who have spent hours listening to recordings of them played half-speed.

From all the above, we can at very least conclude that violins are harder to tell apart than presidents. Just why this is so will be the subject of Violins & Voices, Part 2.

 

 

 

Did Leonardo da Vinci invent the violin?  —  02/21/14

There isn’t a shred of evidence suggesting he did.  Still, the idea comes around every few years, perhaps because it seems fitting that one of the great artists of all time created one of the most enduringly beautiful musical instrument designs.

Leonardo Signature

Leonardo did design a number of new instruments, and made improvements on several existing ones. He invented the viola organista – an organ with mechanically bowed strings in place of pipes. He played lira da braccia and lyre, was reportedly a gifted composer and improviser, and his investigations into sound and vibration foreshadowed future scientific discoveries. All of which to say, Leonardo was spectacularly over-qualified for the job of violin-maker. So it’s not impossible he sketched out something we would now call a violin.

He may even have started building one, but then got distracted and left it unfinished, like so many of his other projects. Or perhaps he met an itinerant luthier, and on impulse tore the sketch from his notebook and gave it away – never imagining the kid would end up in Cremona and meet a guy called Amati, who would run with the idea.

This is pure fantasy. No one knows who made the first violin. The first known examples come from Andrea Amati’s workshop, and are dated decades after Leonardo’s death. So why bring up a half-formed myth in this first post on Violin Science?

Because I’ve been thinking about evidence lately – about what it takes to convince someone, or a whole culture, or just myself, that something is true. If a Leonardo drawing of a violin were discovered and authenticated, his involvement in the instrument’s origins would suddenly become plausible. As it is, violin historians have spent untold hours going through libraries and archives and otherwise scouring the by-ways of Northern Italy in search of evidence about early violins. Thanks to them, the story of the violin remains Leonardo-free.

Historical research has helped answer many important questions about the  violin, but it is ill-suited to addressing the very basic ones: How does the violin produce sound? How do we perceive that sound? Can violin sound be measured? Historians can tell you what has been said or written on these subjects in the past – and this can make fascinating reading. But if you want the questions answered at a fundamental physical level, then scientific research becomes necessary.

It is an odd fact about the violin world that, while historical research holds a respected place at it center, scientific research has long been relegated to the fringes. Whatever the reasons for this, a result is that many of our core beliefs about violin sound are not backed by credible evidence. This doesn’t mean they aren’t true – only that arguments about their truth can never really be settled.

Consider, for example, these five statements:

  1. Violins improve with playing. The longer and the better they are played, the more they improve.
  2. Any competent violinist can separate new violins from old, simply by playing them.
  3. The best Old Italian violins may seem quiet under the ear, but in a large hall will out-project seemingly louder new instruments.
  4. Stradivari and Guarneri del Gesu violins have recognizable voices that distinguish them from one another, and from instruments by other makers.
  5. There is something about the sound of the best Old Italian violins that has never been reproduced elsewhere or since.

I suspect that many players, makers, and dealers will find themselves nodding their heads in agreement with all the above. I myself spent decades nodding in agreement. If you had asked me for evidence, I would have recounted experiences (my own, and those of trusted clients and colleagues) that seemed to leave little room for doubt. I would have pointed to the enormous body of anecdotal evidence that fills violin books, magazines, and more recently, the internet.

I would have said that these five statements are, after all, quite reasonable. Many things get better with age: red wine, Parmesan cheese, balsamic vinegar. Shoes, cars, and pianos all require a “break-in” period. With violins, this just happens to extend over hundreds of years. As for that special something about Old Italian instruments, how else to explain why virtually all top players since the 1800s have chosen Stradivari or Guarneri del Gesu violins as their concert instruments?

Old Italian sound, I assumed, has something to do with the properties of old wood, or perhaps the effects of long-term vibration on its micro-structure. Or else it’s the varnish – the great, lost Italian varnishes that somehow suppress the harsh overtones that bedevil new violins. It could also be the influence of a thin particulate layer between varnish and wood, or the way the wood itself was treated – soaked in brine, perhaps, or buried in manure. And maybe it’s true that wood grown during a mini ice age and harvested while the moon is new has qualities that cannot be otherwise obtained.

So many theories, so little evidence. But in the end, who needs evidence? Violin-making is an art, and works of art must be judged subjectively. Stradivari was a genius, like Bach and Leonardo. No-one would ask for scientific evidence to confirm that a drawing by Leonardo is more beautiful than anything I could come up with. You either see it or you don’t. Stradivari’s elevated conception of violin sound, his visionary reinterpretations of the designs he inherited, and the sheer force of his personality all make themselves felt to the sensitive listener. You either hear it, or you don’t.

Or so I would have argued. Then I began consorting with scientists. Scientists seem to neither believe nor disbelieve these kinds of arguments. They prefer to test them. After some initial resistance, I saw the sense in this and began participating in scientific research. About four years ago I became involved in a series of experiments designed to test how players evaluate instruments, new and old. Thus began one of the most exciting, stressful, confusing, liberating, unnerving, and exhilarating periods of my professional life.

As a result, many things I once believed – including all five of the above statements – no longer seem credible. In future posts I will try to explain why. I will try to lay out the evidence as fairly as possible. You may or may not be persuaded, but allow me in these blogs to make my case. Call it Violin Science.

Leonardo’s signature courtesy Wikimedia Commons