Feature His Demonstration

THE CATGUT ACOUSTICAL SOCIETY NEWSLETTER

Number 11 , published semiannually May 1,1969 The recent meeting of the Acoustical Society of America (April 7-11 in Philadelphia) was organized in full recognition of the Catgut Acoustical Society as a co-sponsor of several of the feature sessions. In particular, there were two such evening sessions, and an all day technical symposium which spotlighted activities and research of many of our members and which are of interest to all of us. The following pages feature reviews of these three sessions by as many of our members, and a fascinating account by- Dean Kimball of the week following the Philadelphia meeting during which many of its participants - as well as others - met informally for a myriad of activities and discussion about fiddles. Tuesday, April 8,1969, 6:30 PM Musical Acoustics Workshop: Recording Techniques for Musical Instruments Arthur Benade and Frank Lewin shared the Tuesday evening program, a discussion of techniques employed in the recording of musical instruments. Arthur Benade described differences in microphone placement, depending on the character of the music being recorded: distant pick-up, preferably in the corner of a rectangular studio, for slow-moving music; close-up position for rapidly moving music. Through diagrams and a demonstration tape he illustrated his re^ searcjj on minimizing the effects of excessively reverberant recording locations through equalizing and filtering. His demonstration consisted of "before and after" tapes of brass and wood w^nd instruments recorded in a very live London church. Frank Lewin described how, as a professional composer, he uses the recording medium as a tool. Through examples on stereophonic tape, he demonstrated various aspects of recording: (a) Acoustics of the recording location — live vs. dead halls, perspective; (b) Method of reproduction, stereo or mono directionality as a means of dramatic expression, the effects of—stereo's greater definition on playback levels; (c) Equalization boosting or suppressing frequencies, exaggerating dynamics, artificial— dynamics (crescendo-diminuendo of a harpsichord, for example), artificial echo, dramatic uses of intentional distortion and feedback, ability to make audible and balance disparate instruments, etc. ; (d; Synchro- nization recording of similar or complementary material onto separate —channels of a multi-track tape. Both Arthur Benade and Frank Lewin conducted their presentations informally, answering questions from the obviously interested audience in the course of their talks and demonstrations, as well as in the formal question-and-answer period. Frank Lewin 2

Wednesday, April 9,1969, 8:30 PM CATGUT ACOUSTICAL SOCIETY Concert-Demonstration of Newly Developed President Bowed String Instruments Arthur Benade There were three distinct categories of 3722 Menlo Road interest. Carl-Hugo Agren of Sweden has Cleveland Ohio Ml2o developed a treble v.iol(*) which he calls Vice President a Magnum. Using electronic and other Virginia Apgar available-to-date research, his aim is to 30 Engle Street produce a viol capable of considerably Tenafly,N.J. o767o more volume, without the characteristic Secretary and traditional "spit-back" under pressure, Carleen Hutchins which is so well known to viol players. 112 Essex Avenue In doing this, however, he does not want Montclair ,N J o7o^2 to lose the distinctive tonal quality of . . a viol. Translating his ideas from the Treasurer drawing board in December 1968 to the real- Warren Creel ity in March 1969 is in itself quite an 1*56 Hamilton Street accomplishment. His points were made by Albany,N.Y. l22o3 playing identical short musical passages Editor alternately with Marjorie Bram (Musical Robert Fryxell Director of New Jersey's "Friends of Early 7355 Drake Road Music"), who was using a reproduction of Cincinnati Ohio 1+52^3 a treble viol built along traditional lines by Dietrich Kessler of London. Mr.Sgren clearly stated his reasons for believing that more volume is a legitimate basis for his project. The second demonstration was of the Violino Grande , developed by Hans 01of Hansson and Bronislaw Eichenholz of Sweden, who were present. Mr.Hansson states that much literature of the baroque and later is ideally suited to the instrument. Additionally, the Violino Grande has captured the imaginations of some major contemporary composers, conductors, and performers here and abroad. This is a somewhat viol-shaped instrument, is unfretted, and is played under the chin. The five strings are tuned in fifths, ascend- ing from the lowest, which is the viola C. Mr.Hansson thinks of it neither as a viola with an E string, nor as a violin with a C string, but as an instrument with its own absolutely distinct individuality. This point was splendidly proved by Mr.Eichenholz, who played a live performance of a suite by Bach which was originally written for the 5-stringed viola pomposa. Following this we heard a taped performance of Penderecki's Concerto for Violino Grande, premiered by Mr.Eichenholz at Dartmouth's 1968 Webern Festival. The Violino Grande is able to return to Sweden warmed by the reception it has met here. The third section of the program involve our old-new friends, Carleen Hutchins' New Violin Family. Yoko Matsuda gave us a most exciting exposure to the mezzo violin. Playing, the first and third movements of the G minor unaccompanied Bach partita on her own *The viol family's members are of various sizes,, and are. disting- uished from the violin family by the following general characteristics: (1) sloping shoulders, (.2) much deeper ribs, (3) 5,6, or 7 strings, which are under less tension than those of the violin family, and (4) fretted fingerboards. They are never properly played under the chin, but "upside down", touching some part of the player's leg. Thus they are also known as the "gamba" family.- Strad, she swung into the mezzo for the second and fourth movements. She is indeed to be admired for her tactile versatility as well as for her violinistic prowess. Her performance was received with vigorous enthusiasm by the capacity audience. It was followed by a taped performance of Frank Lewin 's "Dramatic Suite for New Violins" written for the mezzo,, alto, tenor, baritone, small bass, and contrabass. Both the writing and the performance were of virtuoso quality. This tape has been enthusiastically reviewed by this reporter in an earlier Newsletter. It is the purpose of this report to be more factual than evalu- ative of the instruments themselves, for time will, and indeed is now, a factor in evaluating the functions of all instruments mentioned here. We who listened to this program may very well, have been witnessing musical history in the making. Perhaps an early Cremonese maker occasionally invited friends to his workshop and asked, "What do you think of this instrument as compared to this one, which I made two years ago? ... How do you like this piece of music on it?" And who, then, could have been certain of what would endure and remain of or grow in value and practicality during the next 300 years? — — Marjorie Bram

During this busy week, there was also a meeting of the Trustees and Officers of the Catgut Acoustical Society (April 9, 1969).

The meeting was called to order by Robert Fryxell at 6:36 p.m. He announced the results of the balloting.* President, Arthur Benade Vice-president, Virginia Apgar Secretary, Carleen Hutchins, also a Trustee Treasurer, Warren Creel, also a Trustee A. Stewart Hegeman, elected a Trustee and Robert Fryxell re-elected.

The Board of Trustees now consists of C. M. Hutchins, and J. C. Schelleng, terms running to 1970; W. Creel and F. Lewin, terms to 1971; and A. S. Hegeman and R. E. Fryxell terms to 1972.

Warren Creel submitted an amendment to the by-laws to provide that meetings of the Board of Trustees be called by the Chairman of the Board of Trustees, this to be submitted to a vote after the necessary two week minimum delay.

Motion made and carried that Carleen Hutchins be designated Chairman -of the Board of Trustees for the ensuing year.

Motion made and carried to charge a dollar each for back numbers of the Newsletter, to charge $5.00 for corporate membership in the Society, and that authority to set a policy on markup of the Newsletter to agencies be delegated to the editor.

(*) Nominations by the committee: Mrs. J. Lincoln Piggins Dr. Alice Baker Miss Marjorie Bram (Chairman) Voting by the Trustees

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Motion made and carried that the Society obtain Workmen's Compensation insurance for the typist now working one day a week and for the executive secretaries Alice Cobb and Virginia Kracke.

Motion by A. H. Benade that the Treasurer be instructed to work out and report to the Board a proper means of keeping track of the Society's equity in parts now in process and for future construction of instruments.

Motion made and carried to cooperate with Super-sensitive String Company on strings for new instruments.

Meeting adjourned, and followed by a brief meeting open to all members.

Respectfully submitted,

Warren Creel

The technical symposium on April 11 was originally scheduled to include eight papers; the authors' abstracts are published herewith, courtesy of the Acoustical Society of America. A ninth paper by John Huber was added to the program too late to be included in the printed ASA program. It is reproduced later in these pages. Along with the abstracts is a thoughtful summary and evaluation of this symposium in the words of A. H. Benade. In his covering letter to the editor, he comments: "There is a remarkable unity to the papers, only some of which is imposed by my own viewpoint." We trust that many of the readers will agree, and be heartened by the progress being made in the scientific study of stringed instruments, how they function and behave, and how they affect the listener.

The formal sessions of the Violin Acoustics symposium opened with the paper by Arthur Benade. This paper presented an elementary account of the coupling between the source and the normal modes of the room, and showed its symmetry with the coupling of the microphone to the same modes. At frequencies for which many hundreds of modes lie within a band width of about (l/Trev )Hz of the source frequency, the microphone response is particularly uniform if it is placed exactly in a corner of the room. The uniformity is improved by keeping the source well away (more than a wavelength) from the room boundaries. There are, however, "holes" in the response; fortunately they are sharply localized in space and frequency. These may be dealt with by making three or more recordings with the source moved a wavelength or so between recordings. Each recording has its spectrum analyzed, and the rms sound pressures from these spectra are then averaged. The "holes" -can usefully be removed from the average by omitting any 5Hz wide segments of a given trace which are more than 20 dB below the readings at that frequency on the other traces. The use of several microphones with their signals added defeats the method. Experimental evidence was presented to support the procedure, along with a brief indication of its relevance to extended systems which radiate with isotropic or dipole directivity patterns (the further comments on this appear in the next paragraph)".

The second paper was by Jiirgen Meyer, who reported on an enormously detailed study of the angular distribution of sound radiation from string instruments. The main emphasis of the paper was toward the implications of the directivity patterns for the design of concert halls, and for the placement of players in an orchestra. From the point of view of acoustics, fiddles may be described as acting like monopole (isotropic) sources at low frequencies (u)L/c £l, where L is the breadth of the fiddle). At higher frequencies the radiation tends toward dipole character in its gross features, with the major lobes 5

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Or « normal to the surface of the plates. Shadows cast by the player's body, and reflections from the floor have an important effect on the high frequency distribution. The basic angular distributions constitute a beautiful corroboration of the recent work on radiation from complex vibrating surfaces whose autocorelation length on is small in comparison with the wavelength in air.

Carl-Hugo Agren and Karl Stetson presented the third paper, which dealt with hologram interferometry as a means for learning about the vibration states of viol plates. Basi- cally the technique is to photograph the interference pattern produced between a photo- graphically recorded hologram of the stationary plate and a hologram produced by the same plate when it is excited in one of its vibrational modes. The beautifully clear pictures obtained in this way contain enormously more detailed information than do the familiar Chladni figures. Vibration-shape data of this sort have implications for those interested in radiation from a violin as remarked in the preceding paragraph. A more important use for them comes from the fact that they allow one to make rapid semi- quantitative assessments of the effect of -carving wood (at a given point) on the frequencies of a large number of the normal modes. This could well be developed into an extremely powerful aid to the violin maker in tuning his plates without extensive testing. People who are interested in studying the way in which the string is coupled to the violin body will also find vibration patterns of this sort useful, because one can use them to make driving-point impedance estimates for the spots where the bridge feet rest. One can hope that the next few years will see a development and simplification of these holographic techniques , and that they will be widely used.

Hans Olof Hansspn described the acoustical design which lay behind the construction of his Violino Grande (which had been demonstrated earlier by Bronislaw Eichenholz). It is built somewhat larger than a violin, and has its upper four strings tuned to the usual violin pitches. The fifth string is tuned to C3, as is the bottom string of the viola. The acoustical design starts with a deliberate placement of the main air resonance below the bottom note of the instrument. The scaling of the plate thicknesses etc. is then chosen to give a reasonably uniform distribution of resonances across the musical frequencies, to give a tone color that is remarkably constant as one goes from note to note throughout the scale. This is of course in marked contrast to the deliberately- arranged super-position of strong resonances which plays such a- large role in determining the characteristic voice of a conventional violin. This difference in tone color between old and new has considerable interest for contemporary composers, as was well demonstrated at the concert. This paper also reported on a series of chromato- graphic experiments which identified egg-white to be the basic ingredient of primer used beneath the varnish of old Italian violins.

The second session of the symposium was opened by James Beauchamp: He described the technical details of a four-stage computer program for making spectrum analyses and syntheses of time varying musical spectra. It was particularly interesting to see a l6mm film presentation of a violin sound spectrum during the startup of a tone. There is a dying away of "noise" at the beginning, as the initial scrape of the bow locks the string vibrations to itself, and also as the program instructs itself on how to refine its analysis of an incoming signal. Following this comes a building up of the various spectral components until the steady state is reached. These components do not build up at equal rates, nor do they build up steadily. Data of this sort should be of great use to anyone interested in the theory of self-sustained oscillations. The time variation of intensity during the course of each cycle of vibrato was also interesting. One might expect this to be only a little change, since the string frequency is altered only slightly by the rolling finger of the player. We can deduce this expectation from the principle of adiabatic invariance, which shows that the fractional change in intensity is equal to the fractional change in vibrational frequency. Observation of the phase of the intensity variation relative to the phase of the frequency alteration would help settle whether the effect is controlled by varying damping produced by the player's finger, or by more subtle causes .

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It was most unfortunate that John Schelleng was not able to read his own paper on the Bowed String; however, Carleen Hutchins succeeded in conveying the elegance and simplicity which is so characteristic a feature of Schelleng fs work. The basic question to which he ad- dressed himself was the extent to which the voice of a stringed instrument is determined by the string, and how much depends on the nature of fiddle box and its coupling to the string and to the concert hall. If one brings a small magnet near a vibrating string, a time varying voltage is induced, proportional to the velocity of the string at the position of the magnet. The placing of magnets next to all four strings of a cello, near the bridge, and the connection of all the strings in series to a tape recorder permits one to record the signal characteristic of string velocity. The use of an RC integrator also allows one to record a signal that represents the displacement of the string (and hence of the force which it exerts on the bridge). Recordings of these two sorts were played, and contrasted with normal microphone recordings of the same cello. Acoustical theory shows that if the string were dominant, the radiated sound would be simply related to a combi- nation of the sounds belonging to the two string-pickup sounds. There would be little variation in tone color in going from one note to the next. It was clearly apparent that the cello body is introducing a great deal of complication into the spectrum of a normally recorded tone.

Paul Boorasliter and Warren Creel presented a most stimulating and informative paper on the usefulness of musical tones for auditory research. They start from the point where the sound signals enter the nervous system, after they have run the acoustical gauntlet of being generated mechanically, transmitted through the air, passed through the physiological apparatus which constitutes the ear. There is mounting evidence that the mind builds itself matrices of temporal patterns which are then compared with the patterns evoked by the incoming stimuli from various sense organs. When the stimulus pattern and the matrix pattern match (sufficiently), we respond with behavior based upon "recognition" of the incoming stimulus. There are fascinating implications in this for the theory of rhythm in music. In addition, one finds a large number of new reasons for the universal importance of the octave, fifth, and other simple intervals in the world's music, quite apart from the rather strong agruments which may be deduced from the purely physiological and acoustical sides of the subject. It is possible to diag- nose various diseases with the help of auditory tests which make use of the way in which the mind compares temporal patterns. A striking example of such a test involves the measurement of the tone-pulse duration time required for a person to recognize the "quality" of tone bursts of varying complexity (sine, square-wave, frequency modulated sine, etc.). A normal person recognizes the complex signals somewhat more quickly than he does the simple ones, because the complex tones give more cues for matching with the matrix than do the simple ones. Persons with deficient functioning of some portions of the brain stem -and cortex require considerably more time to deal with complex signals than with simple ones. This is because damage to a system causes more or less frequent, but' random, "dropouts" in the matching process. The comparisons must then be made repeatedly until enough segments of partial matching have been collected that a recognition decision becomes possible. Beyond a certain amount of malfunction the "forgetting rate" exceeds the collection rate of partial patterns, and there is no recognition at all.

The acoustic properties of wood were discussed by Eugen Skudrzyk and Yoshimasa Sakurai. The elastic properties of wood are extremely anisotropic because of its grain (a fact which has made it very useful to the makers of musical instruments for centuries). This is, of course, well known. The elastic constants of wood are so related that the shear modulus joins with Young's modulus in the formulae for bending stiffness in an amount which depends drastically on the direction of bending. It also depends strongly on the ratio of the bending "wavelength" to the thickness of the sheet. The imaginary (i.e., damping) part of the shear modulus shows the same behavior, so that a thin board (such as a violin plate) shows a relatively low damping for its lower frequency modes, and high damping for the upper modes, with a fairly abrupt transition between. It would appear that with proper proportioning of the wood, not only should the resonances of such a plate be placed at the right frequencies, but also the lower, more important resonances should be lightly damped for strong response, leaving the higher ones heavily damped so as to remove excessive edginess from the tone. The final paper in the symposium was a preliminary account by John Huber of his use of Carleen Hutchins' equipment for the acoustical testing of guitar plates and of complete instruments. This work has just begun, so that it is not possible to enunciate any general principles. However, it did seem that the guitar is characterized by a larger number of sharp resonances than is the case for the violin. This is perhaps to be ex- pected, since the span of the plates is larger and the bracing rather complete.

A. H. Benade

FIVE DAYS AT 112 ESSEX AVENUE -- Dean Kimball Since many of our members have not had the privilege of visiting the home of Morton and Carleen Hutchins in Montclair,N. J., I thought everyone might enjoy an account of a few days activities there immediately following the meeting in Philadelphia. Let me introduce the principal people involved during those days : Morton and Carleen Hutchins were our gracious hosts. Mr. Carl Hugo i_gren of Akersberga Sweden (who presented a paper in Philadelphia) and who is a professional research photographer as well as an enthusiastic builder of beautiful viols. Miss Marjorie Bram of South Orange, N. J., violinist, teacher of music, conductor > composer, and Director of "Friends of Early Music ", a group performing on a consort of viols. Mr.Warren Creel of Albany Medical College (who presented a paper in Philadelphia) Mr.Daniel Haines of the engineering department of Princeton University, a specialist in vibration problems. Mr.Hans Olof Hansson of Sollentuna Sweden (who presented a paper in Philadelphia). He is also Research Director at the Sieverts Cable Works and a builder of beautiful instruments in the viol and violin family. Mr. Dean Kimball of the engineering department of Antioch College and the author of these observations as well as a pupil of Carleen Hutchins. Mr.Donald Ludwig of the mathematics department of New York University Mr. Jurgen Meyer of Braunschweig, Germany (who presented a paper in Philadelphia). He is with the German Bureau of Standards and is also an accomplished violinist. Also present as permanent residents were Richie, the Siamese cat; Satan, the talking crow; and four turtles who had not long since emerged from winter hibernation in a spare refrigerator. Now with the people introduced I will describe in part the activity from Monday through Friday of the week following the meeting of the Acoustical Society of America in Philadelphia. Much of Monday was occupied in crating and preparing for shipment the new family of instruments. These were to be shipped air freight to Chapel Hill,North Carolina, where Carleen will lecture on them April 23 and 2^(*). It might not seem that shipping the instruments was a very big operation, but by the time the large bass is housed in its special case (which slightly resembles a mummy case) it is more like shipping a small house than a musical instrument. With the first load in the übiquitous VW Microbus, Carleen headed for the airport. However, the first shipper she called on was unable to accept the shipment because the door of their planes was not large enough to pass the big bass in its box. The second airline contacted was able to ship the instruments but required some persuasion. It seems to take seme

*As this goes to press, the editor has a report that the instruments arrived safely and that the lectures were a great success.

8 time for the shippers to get used to the idea of shipping a large and very valuable string bass in spite of their advertising which implies they will ship everything from an ostrich egg to the ostrich itself without batting an eye. With the first trip to the airport completed a second had to be made, because the microbus can't handle the whole violin family crated even with both back seats removed. The second trip was somewhat of an anticlimax except that it had to be made during the early part of the traffic rush hour, which is quite something around Montclair. The shipping along with a few dozen other lesser doings disposed of Monday. Tuesday, a trip to the Bell Telephone Laboratories at Murray Hill had been arranged for the foreign visitors. Warren Creel and I were also along on that delightful trip. Since the VW bus transports people as well as fiddles, the rear seat had to be re- mounted before leaving for BTL. We arrived about 11:00 and were introduced to Jean-Claude Risset who was our host for the day. After collecting the group and doing some preliminary sightseeing, we were treated to an excellent luncheon in one of the BTL dining rooms . The only disappointment there was that Carl Hugo Agreh found BTL does not serve beer in the company dining room. After lunch we had an interesting visit to the large anechoic chamber where BTL conducts much interesting research in all manner of investigations of sound. James West was our source of information and guide for that part of the visit. The room itself was most fascinating. The floor is a slightly jittery open wire mesh (meshes approximately 2 inches square ) which suspends one about in the center of the room top to bottom. C_ie could clearly observe the inverse square law for sound versus distance since there was no reflection from the walls. The chamber would make a great place to concentrate except that it is so quiet one tends to get a bit- of a headache and feel a bit queer with none of the normal small sounds of life present. From the anechoic chamber or "free space room" we went for an interesting visit with Manfred Schroeder, specialist in various fields of acoustics, particularly speech and room acoustics, who discussed various problems of concert halls, and especially Philharmonic Hall on which he has been a consultant. After leavinghis office we saw a fascinating demonstration by Mr.Pierre Ruiz of work being done in synthesizing sounds from the differential equations of the strings. The action of the string excited by plucking, bowing, and being struck by a hammer as in a piano was completely synthesized by a small digital computer and the results displayed on a cathode ray tube. After we had seen the simulated string action, we then heard sound tapes which had been recorded directly from the computer. Sounds were thus produced without an air molecule having been "wiggled" until the sounds issued from the speakers of the tape recorder. The sounds were surprisingly similar to those which they were intended to imitate in spite of some simplification of the equations describing them. As much as the word has been abused, I can only say "fantastic". A visit to Mr.Robert Collier's office developed into a discussion of various holographic techniques and their application to the study of vibrating violin plates. Mr.lgren had brought along his photographs of the holograms made of his viol by potentials Karl Stetson during its construction. Everyone was very interested in the of this method for investigating vibrations in the string instruments. Risset. From there we went to the laboratory of our host for the day, Jean-Claude tones and has He has done a great deal of work on the analysis of musical instrument later bibliography). an extensive publication with M.V.Mathews on this subject, (see analysis can often come successful synthesis. We had the opportunity Out of effective conven- where not only was heard the simulation of different to hear "computer music" quality tones, but also output from the computer which owed its tone tional instrument one's orientation no existing instrument but the computer itself. Depending on to are rapidly he may or may not like the fact, but science and music and approach, good becoming more intimately entwined. Perhaps in seeking to learn how to build

9 fiddles,l am learning an obsolete technique much too late. (Hope I can dodge all the tomatoes). Thus ended our enormously interesting tour of BTL at about 6:00 FM. Wednesday morning, Carl Hugo ifgren arrived about 9:00. He had discussed possible bridge designs which might improve his magnum viol and was anxious to try out some of the new bridge shapes and woods. He spent some time in the workshop cutting out, filing and fitting new bridges. Somewhat later, Mr.Hansson and Miss Bram arrived. Miss Bram brought her viola d'amore and treble viol as well as a quantity of excellent ice cream. At noon we all went to the beautiful home of Miss Virginia Kracke for a tasty lunch, but with many things yet to be accomplished, we returned to 112 Essex Avenue early in the afternoon. Later, Carleen turned in a virtuoso performance by preparing dinner, carrying on a lively conversation and starting a test on Carl Hugo's viol with her electronic equipment. It's a wonder the lamb roast didn't end up being roasted inside the viol, but somehow everything got in its right place. It's a shame because it would have been fun to have had a resonance curve made for the roast. In the midst of this activity Mr.Hansson was making alterations on Miss Bram's viola d'amore in the middle of the kitchen table, Carl Hugo was trying his viol with the new bridges, CBS was calling about arrangements for a visit to its studios for i_gren, Hansson, and Meyer, and Satan the crow was shouting variously interpreted imprecations at all of us. The turtles seemed least disturbed as they slid noise- lessly about in their private bathtub. In the course of the electronic tests, Richie (the beautiful brown cat with star sapphire eyes) parked himself on top of the audio sweep generator, where it was nice and warm, and fell contentedly asleep. The only trouble was that his hind, leg tended to slip down over the top of the dial so that it was difficult to set the calibration on the oscillator. As the testing became more concentrated due to time pressures, Mort and Miss Bram took over preparing dinner so that Carleen could devote full time to testing. We ate in relays, thus permitting the tests on the instruments of Agren and Hansson to be finished in time for them to have the results before returning to Sweden. Later in the evening Daniel Haines and Donald Ludwig arrived to take part in the discussion. After the tests on the two viols were finished, a resonance curve was run for Dan Haines on a flat rectangular spruce plate with approximately the same area as a violin belly. Since the equations of vibratory modes are somewhat more manageable for a rectangular plate than those for the violin belly, Mr.Haines hoped to check the theoretical vibration of a flat plate with the actual results for a sheet of spruce as obtained on Carleen's apparatus. These were finished about 11:00 PM and thus ended an incredibly full but delightful day. It is probably superfluous to remark that one may see why Carleen sometimes doesn't make as much progress as she would like in her own research. Thursday, Carleen and Mrs. Winifred Flatt, the secretary who has been working on Catgut affairs for over a year, managed to answer some twenty letters that had accumulated over the previous week. Friday saw the visitors off and Warren Creel initiated into the mysterious rites of becoming treasurer of the Catgut Acoustical Society (bless his unflappable courage). So ended five days at 112 Essex Avenue.

But after this delightful diversion in Montclair, we should return to a report of many other activities prior to the Philadelphia meeting. One of the most exciting and rewarding concert -demonstrations of the eight instruments of the new violin family took place last November before the American Philosophical Society in Phila- delphia. This was made possible through the interest of one of our members,

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Dr. Henry Allen Moe, President of the American Philosophical Society, and Dr.George Corner, its Executive Officer. Samuel Singer of the Philadelphia Inquirer wrote "Scientific principles put to practical use had an intensely musical demonstration Thursday evening before the prestigious American Philosophical Society. The instruments were played by eight musicians from Miami (0. ) University in the Society's library, across from Independence Hall. "Instead of the usual violin, viola, violoncello, and double bass there were eight instruments ranging from the 15-inch treble violin, an octave above the conventional violin, and fiddles tuned in fourths or octaves down to the double bass - but one much larger and more resonant than the usual bull fiddle. "Whether a musician played an instrument corresponding in pitch to the conventional fiddle, or whether his violin was tuned between two of the others, he had to learn how to play it, because of the difference in size (and string length) as well as pitch. "Moreover, the music - by antique and contemporary composers - had to be arranged far this ensemble. This had been done by Joseph Bein of the Miami University music department, who conducted the octet of accomplished players. "The test of any musical instrument of course is: flow does it sound? These instruments sound great. "Not only is there exceptional clarity of tone, apparent without shrillness in the small instruments, and sonorous without sonic boom in the bass violins, but there is a marvelous homogeneity of tone along the entire register. "The notes could easily pass from one adjacent instrument to another, and the eye would have to catch what the ear might miss because of the uncommon smoothness. "The octet opened with a Vivaldi Concerto Grosso in D minor that was finely balanced in all ranges. Mennini's Arioso, somber and stately, contrasted with three lighter "Pieces en Concert" by Francois Couperin. Ease of balance was further demonstrated in the vigorous Fugue from Foote's Suite for Strings." Asked by Dr.Moe to comment on the performance, both Dr.Michael Heidleberger and Dr. Samuel Goudsmit of the APS expressed much interest in the research and development of the new instruments and the hope that some day all scientific knowledge could be used in musical and artistic directions such as this. The musicians were Lucinda Myers, treble violin; Allen Bein, soprano violin; Roy Mann, mezzo violin; Paul Van Ausdale, alto violin; Elizabeth Potteiger, tenor violin; Ronald Crutcher, baritone violin; James Veith, small bass violin; Ronald Naspo, contrabass violin. Preceding the concert, Carleen Hutchins gave a short illustrated lecture on the development of these instruments . In preparation for this concert, the musicians had had the new instruments during the summer and early fall for a series of intensive practice sessions and rehearsals. The group played several concerts in the Ohio area including the Ohio String Teacher's Association, Wittenberg University, and Miami University. In the latter two of these, Carleen Hutchins lectured on the research and development of the instruments. As a result of this experience, the Miami University musicians under the leadership of Joseph Bein and Elizabeth Potteiger, both members of the Oxford String Quartet, now have four of the new instruments and are working toward an intensive summer session next August on Lake Winnepesaukee in New Hampshire. They will be joined by the composer Robert Haskins, also a string player, who will explore the musical potentials of the new instruments and compose for them. Mr.Bein and Miss Potteiger plan to continue their work on the selection and arrangement of early music suitable to the unique characteristics of the new violin family. 12

On February 2*4-, Carleen Hutchins gave an illustrated lecture-demonstration on the* new violin family to the Adult School of Montclair,N.J; and on March 5 to the Scarsdale,N.Y. Womens Club. During the week of April 21, Mrs .Hutchins and the eight new instruments took part in the Fine Arts Festival of the University of North Carolina at Chapel Hill on the invitation of Dr. John Sarratt and Dr. Lawrence Slifkin. This included a symposium for the physics department and a lecture-demonstration.

The exciting new sounds from the tenor violin continue to create a great deal of interest whenever it is played. During the Christmas holidays, the concert cellists Margaret Aue and Laszlo Varga, both now residing in California, just happened to come to 112 Essex Avenue on the same day. They played the tenor and baritone violins back and forth with a good deal of interest and excitement, at times playing snatches of the great solo literature for cello or combining in parts- of the string literature, joined now and then by Bill Carboni, violist in. the New York Philharmonic who had brought Varga in, till the walls rang with the sound.' Both Aue and Varga expressed real interest in some day performing the tenor violin in a concerto with symphony orchestra. Mr.Varga is particularly interested in the violoncello-piccolo which is a smaller than average cello with five strings, C-G-D-A-E. He suggested a number of pieces for this instrument which would be admirably suited to the tenor violin, Later he wrote saying: "Thank you for your hospitality and an introduction to your family of instruments. They are really a premising development for the future, and I am excited about their potentials." C.P.Rogers continues her work on a new concerto for tenor violin and orchestra, which she indicates is well under way.

While all these musical activities have been going on, the Projects Committee has held several lengthy discussions to ponder the question what topics of study (musical, scientific, etc.) are legitimately supported by the Society. Anticipating action from this committee, the Board has appointed Mrs.H.L.Cobb and Miss Virginia Kracke as Co-executive Secretaries whose responsibilities include publicity, administration, proposal writing, and in general expediting our activities. These ladies bring to us a wealth of experience in advertising, writing, publications, and civic affairs, and have a keen interest in music and the general objectives of our Society. We welcome them as members and as key contributors to our future projects. Their presence on our staff is possible through the Martha Baird Rockefeller Fund for Music.

The Projects Committee has tendered the following report: The Projects Committee, made up of Warren Creel, chairman, Patsy Rogers and Carleen Hutchins, in the course of several meetings, has boiled down the many details and concepts to two general approaches: A. Education and development. B. Research and construction. The first of these includes such activities as the concert and symposium just carried out at the convention of the Acoustical Society of America in Philadelphia, the concert at the American Philosophical Society last November, and the various lecture demonstrations by C.M.Hutchins and others. Future plans involve several activities which depend on each other. For example: to have a group of performers trained over a period of time to play professional concerts on the new family of instruments, it is necessary to build more of the new instruments. Although there are duplicates of several sizes, there is still only one complete set of all eight. Events are outrunning plans in that the group from Miami Univer- sity (Ohio) who have played a number of concerts on the new instruments requested a summer workshop session to practice the instruments and explore the musical potentials of the new sounds. A small grant has already been obtained to commission a composer to join the group and write new music. This exploratory session will be at the Hutchins' family camp in New Hampshire for three weeks this summer ,±n the hope that such a pilot siTudy will lead to a comparable workshop session as part of an established music center the following summer. Patsy Rogers has undertaken to develop a series of cost estimates for a series of related activities including subsidy of a performance group, construction of several sets of the new instruments, production of a disc recording using the new fiddle family, and composition and arranging for the new instruments. The second aspect, research and construction, lends itself to planning as separate projects for which the committee will draw up grant proposals subject to approval by the Board of Trustees. These include: (1) Construction of ten off-designed violins of conventional size and outline but with certain known variables built into each and the results evaluated by several test methods including multidimensional scaling of comments by musicians playing the instruments. (2) Study of the ultrastrueture of wood suitable for violins. (3) Further study of holography as a means for studying the vibration patterns in violin plates. (4) Investigation, following Schelleng 1 s findings that the less varnish used on fiddles the better, of the acoustical effects of both modern and old types of varnish and filler on flat spruce plates with violin shape as well as rectangular plates with different grain orientations. Publication and library reference service on stringed instrument data is another area of committee interest. Now for a Finance Committee to get the funds for these projects. Respectfully submitted, Warren Creel **************

Recent publications by members are: (l) "Analysis of Musical-Instrument Tones", Jean-Claude Risset and Max V.Mathews Physics Today, V01.22, Feb. 1969. (2) "Sound Production in Wind Instruments", A.H.Benade and D.J.Gans - Annals of the New York Academy of Sciences, Vol. 155, N0v. 20,1968. (3) "Misurazione Acustica di Violine", CM. Hutchins and F.L.Fielding - Sapere, VoI.LXX, N0.709, Feb. 1969 (a somewhat condensed version, in Italian, of the article "Acoustical Measurement of Violins" which appeared in Physics Today, July, 1968). (k) "On the Propogation of Sound Waves in a Cylindrical Circuit", A.H.Benade - Jour.Acoust. Soc .Amer., Vol.kk, N0.2, August 1968

13 14

TREASURERS REPORT: Balance, 0ct. 1,1968 $1230.97 Income $1+35^.27 Dues $390.00 Contributions 3922.27 Sales 1+2.00 Expenditures 3896.07 Equipment 368.06 Reprints 83.21 Postage 183.01+ Printing and Stat. 1+5.62 Secretary 396.25 Newsletter ioo.6i+ Telephone 223.75 Tax Accountant i25.00 Miscellaneous I+BB.oo Performers 100.00 New Instruments 1781.05 Bank Charges 1.1+5 Balance, April 1,1969 $1689.17

Respectfully submitted, Warren Creel, Treasurer

Found in the columns of the VIOLIN TIMES (London) of March 15,1895 An account of an introduction to an audience of an eminent violinist, who has been recently pouring in the Western States of America, Is unique in its way, and has been going the rounds of the Press, musical and otherwise. Taken originally from HARPERS MAGAZINE, it reads as follows: "Ladies and Gentlemen," began Colonel Handy Polk, the well- known real estate agent, stepping to the front of the stage and addressing the audience. "It is my privilege -this evenin' to interduce to you Signor , the notorious furrin fiddler, who will endeavour to favour us with some high class and A No.l violin playin'. The signor was born and raised in Italy, where fiddlin' is not merely a fad, but as much of a business as politics is in this country, and when it comes to handlin' the bow he emphatically knows whur he is at. He hasn't dropped into our midst by accident, but comes under the auspices of the Literary Society, which is payin' his wages and backin' him to the last gasp. So let it be understood that if you happen to have any criticisms to offer, you are to do your kickin' t"b the Society, and not to the signor. I'll jest add that if you expect him to swing the fiddle around his head or play.it under his leg,, like we used to skip stones across the swimmin 1 hole when we were little boys and girls, you may jest as well go right now and git your money back from the doorkeeper, for the signor hain't that kind of a player. That's1 all I have to say at present. Start her up, signor." THE APPLICATION OF ACOUSTICAL TESTING METHODS TQ THE GUITAR John Huber The guitar has never had its Stradavari, and yet has survived the duration of man's need for music since its ancestors were developed in the ancient near East. Possibly its lack of perfection has contributed to its longevity by allowing easy adaptation to changing needs in contrast to the lute, for example, which was trap- ped into a time period by its yery specialization. The guitar has, for long periods in its history, been essentially an instrument of the people and only occasionally has risen above that station to legitimately play "serious" music. Due to Andres Segovia, increased leisure time and educational level, and the advent of the nylon string, we are now entering another period in which the guitar is establishing new \ limits. Presently adequate for popular use, it verges also on acceptance by the elite if it can meet but one criterion; to loudly speak from the concert stage without losing its quality of voice— in other words, volume. Although the problem was clearly visible, its solution was nowhere in sight. After many false paths, it was found that the Catgut Acoustical Society had developed techniques of testing and analysisU; which when tried were found applicable to the guitar. Violins and guitars are related only superficially, but the resonance of wood and air can be located with the same techniques. The top of the instrument is driven by a transducer fastened securely to the center of the bridge and which receives amplified signals from a frequency generator. The output is picked up by a microphone and measured by a sound level meter coupled to a recording pen. The resulting graph is much more easily read and interpreted than my previously accumulated mountain of Chladni patterns as it more closely approximates what the trained ear hears and, in fact, made the Chladni patterns more intelligible by giving a measurable account of the change that occurs with a shift in nodal lines. Certain traditional rules exist for the establishment of basic guitar dimensions and, given a vibrating string length, one can proceed to reduce the corresponding instrument measurements. W These rules vary according to the region of Europe in which the guitar is made, but essentially assume polarity around the southern half of Spain, the Mediter- ranean school, and southeastern Germany, the northern school, with other regions more geographically than acoustically influenced by their relation to one or the other of the poles. The northern school has a long history of violin making and this has neces- sarily affected their guitar design, whereas the Spaniards, unencumbered with violin tradition, have had sufficient success with the guitar to make 1t their national In- strument In both serious and popular music. Spanish rules were as a starting point. therefore used

A well known northern" style guitar, commercially successful and accepted as a quality instrument by experts in the field, has the spectrum shown in Figure ponding 1. The corres- curve for a typical professional grade Spanish instrument is shown in Figure 2. It 1s immediately apparent that the overall level of response of the Spanish instrument is vastly different from the first even without locating resonance points reference. for

Basic dimensions being established, the type of structural reinforcement of plates, (i.e. bracing}, was dictated by the cumulative experience of repairmen in the industry, traditional patterns, and Chladni patterns made to approximate those found on selected instruments at selected frequencies. After months of experimentation, pattern a bracing was worked out, materials for its component parts selected, and re-evaluation in depth using the Hutchins technique was begun. The back of the guitar was braced so as to pre-stress the curvature back in the lateral axis; longitudinally was designed into the shape of the sides, resulting in an O ed just braced Ca^ below the soundhole. The profile this braced burun^ttLlbut unattached KfLbackPOI^K^exhibits is response to a multitude of frequencies

15 ** FREQUENCY IN PER

Fig. 1 "Northern" Style Guitar

FREQUENCY IN PER

Fig. 2 Spanish Guitar by Manuel Reyes; 1966

The sound board, with its carefully positioned soundhole of a size determined by the formula for a Helmholz resonator (which the old Spanish rule correctly antici- pated) was braced in a mixed pattern of long and short braces tapered so as to strengthen the area weakened by the soundhole and yet permit peripheral flexibility. Species of wood were selected for braces according to density to ODtain maximum vibration transmission in necessary regions of the top. Here the response at the same input level as other charts was such that it went off scale, was lowered ten decibels and repeated; hence, the double profile (Figure 4). This same top, when glued to a side assembly (without back) is still very active, but obvious depressions in the curve now show (Figure 5). The back (Figure 3) when joined to the top side assembly, shows a recovery from the depressions, while re- taining major peaks of resonance (Figure 6).

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O The addition of a neck to the assembly did not substantially alter the shape of the graph (Figure 7). The addition of strings tuned to pitch to the body apparently lowered the overall response in decibels, but did not substantially alter the shape of the graph (Figure 8). The completed instrument gives the following profile which closely approximates the graph of the Spanish instrument used as a standard (Figure 9). At this point the effect of curvature in the sides is unknown. Assuming that resonance in flat plates is simpler, therefore more easily analyzed, one is reminded of the attempt by Felix Savart in 1819 to analyze the same problem. (3) He designed a trapezoidal violin which was declared by an elite panel of jurors to be equal to a Stradivarius in tone. A sketch of his instrument was scaled up to guitar size and reproduced in wood. This interesting diversion gives the profile shown in Figure 10. The graph shows unmistakable guitar characteristics in spite of its distinct physical differences. In- sufficient data prevents drawing any conclusions about trapezoids, but one can possibly predict that considerable latitude exists for changing guitar design without changing essential guitar characteristics. In conclusion, the guitar's potential for development is sufficient to warrant considerable attention in the future. While guitar design has remained essentially static for the past century, new techniques now enable us to gain new insight into its nature and hopefully may permit us to elevate its status to full fledged membership in the string fraternity. (1) "The Physics of Violins", C. M. Hutchins, Scientific American, Nov. 1962. "Subharmonics and Plate Top Tones in Violin Acoustics", C. M. Hutchins, A. S. Hopping, F. A. Saunders, J. Acoust. Soc. Am. 32, 1443 (I960). "The Violin as a Circuit" J. C. Schelleng, J. Acoust. Soc. Am. 35, 326, (1963). (2) "Die Gitarre und Ihr Bau", Franz Jahnel , Verlag Das Musik Instrument, Frankfurt am Main, 1963.

(3) "Felix Savart (1791-1841), Physician-Physicist," Victor A. McKusick and H. Kenneth Wiskend, Journal of the History of Medicine and Allied Sciences 1959, Vol. XIV, Number 4.

REQUIREMENTS FOR SOUNDING BOARD MATERIAL — John C. Schelleng The title refers to substitutes for wood with particular reference to the fiddle. The principles involved in selecting material for other instruments are similar in many respects.

The expert luthier is painfully aware of diversity in the properties of woods destined to become tops or backs of instruments. If there were such a thing as standardization for this material, the problem of making a second instrument like a first would be mainly one of dupli- cating dimensions thickness and arch ~ no mean task it is true, but one that is clearly defined and one that— we could teach a clever machine to perform.

When we look at the great variety of new materials that modern technology has put at our disposal, we wonder why luthiers insist on using an old-fashioned one like wood, and ask: Why not use a modern plastic? Wood for fiddles is expensive, variable, hygroscopic and except for inferior instruments unsuited for quantity production. The answer to this recurrent question is this: As soon as someone produces an artificial material as good as wood, it will without any doubt be widely used in high grade instruments . We all hope that the day will come when this is so. But with all its shortcomings, wood is a remarkable material and its equal may be slower in coming than our devotion to progress leads us to expect. Nevertheless, we would unwise not to entertain the hope. / . be r (cont.page o^\dO)

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' Opinions differ as to the most urgently needed direction for fiddle research. The one most appealing to the artist in us is to find how repeatedly to equal or indeed to surpass the quality of old Italian instruments. This jLs_ important. But against the need. for outstanding instruments,how shall we weigh the need for merely excellent ones? Is it more important to satisfy a few virtuosos than to encourage the thousands of less prominent talents, both professional and amateur? Should one encourage passive listening more than active partici- pation? In a roll call in the string sections of our thousands of symphony orchestras, how many excellent fiddles would we find and, by comparison, how many excellent automobiles?

In the development of the violin, a long period of experimentation with various species of wood preceded the final settling upon the spruce-maple pair as standard for top and back. The knowledge that conifers are the best for the top plate seems to have come early, while the choosing of picea excelsis, or Norway spruce, came later. The maker was always particular picea about what excelsis he would accept; it had to grow under certain climatic conditions 4 on the proper side of a hill with certain conditions of the soil and could be taken only from a suitable section of the trunk. More variety was permitted in the backs, which however were usually from deciduous trees. This wider range of choice no doubt reflected the lesser importance of the back in radiating sound. Up to the time of Nicolo Amati poplar and pear found considerable use and made good fiddles, but they have the reputation of having a "veiled quality" and not "speaking" well. Free from these acoustical shortcomings, maple i is also unsurpassed in visual beauty.

The hope that an artificial material can provide a step in the direction of excellent instruments available in quantity implies the hope that it will be permissible for the material to be everywhere the same. In the fiddle there is a significant difference going from the middle where the annual rings are close, laterally to the ribs, where the growth is heartwood. However, the production of artificial materials will have enough difficulties without the additional requirement of imitating wood in this respect. In the first trials one should be satisfied with materials everywhere the same, particularly since the degree of difference in the quality of the resultant instrument is not known and indeed might possibly be counteracted by using modified thickness contours. Wood also has variations from point to point of a more random nature. Some believe them to be important in giving more resonances in the frequency spectrum. This however is a view not universally held, and should not discourage experimentation in new materials. In setting down the more important properties of a substitute, the first thing to recognize is that isotropic materials are of no value: The material must be orthotropic like wood, much more flexible in one direction than it is 90° therefrom. In violin spruce the elastic modulus across the grain is roughly one fifteenth that along it, a ratio that peculiarly recommends it for use in fiddle plates, whose length must be more than twice the width to accommodate the necessities of bowing and fingering. If we were to make an instrument in which length equalled width, a nearly isotropic material would be suitable; the "tuning" of the plate would then be about the same in both directions. This is also desirable in the normal fiddle, and one of the means of accomplishing it is by reducing transverse stiffness. Any more precise statement is precluded by the complications introduced by bassbar and f-holes.

We may be sure that if an isotropic material were used in violin plates it would change the vibrational character of the assembled instrument in two important respects: (l) the geometric shape of nodal patterns of modes, in particular their predominantly lengthwise direction (except at high frequencies), and (2) the relatively even distribution of resonances in the frequency spectrum. Concerning the first of these, orthotropicity normally cooperates with the bassbar in establishing the same phase in radiation from the two ends; the second is necessary in maintaining tonal balance throughout the range.

For maple the orthotropic ratio in modulus of elasticity is much less than in spruce, being about k to 1 rather than 15 to one. This is suggested in the nodal diagrams of the isolated plates: for lowest frequency the spruce top has lengthwise nodes while in the maple back they are transverse. Whether a rationale for this design was in the minds of

20 21

the old masters we do not know. They may have felt that the plate which is vibrated by the bridge directly should be the more flexible of the two, and that the back should be designed to enable the top to do the major part of radiating, a principle on which viols had been designed. In the violin the top plate provides about 2/3 of the radiated sound pressure.

An additional requirement in the back is that it be the stronger member in withstanding the static downward force of the strings, which is of the order of 25 pounds. Deciduous trees usually have greater ultimate strength across the grain than conifers.

Having given for each member the desirable ratio between its two Young's moduli, which are therefore to be duplicated in the new material, one needs next to establish something about their absolute values. This however cannot be done independently of a consideration of density. What we are really concerned about at this point is the admittance (reciprocal of impedance) that a r properly adjusted plate will have; in order to maximize radiation this should be as large as possible. Two plates, suitably arched, can perform similarly even though elasticities and densities are different^ provided that their values of E/p3 are the same; mechanical admittances are then the same, since in fiddles properly made admit- 3 tance turns out to be^ proportional to (E/p3) S. This is sometimes expressed as c/p, where c, which equals (E/p)^, is dimensionally a velocity and is sometimes thought of as velocity of compressional waves in the wood though it enters equations for bending waves merely as a mathematical parameter. Thinking in terms of Young's modulus and density (i.e., E and p) one sees that 1% increase in admittance requires a 2% increase in E, but only a 2/3s. decrease in p; this underlines the great importance of lightness in top plate material, and constitutes an important advantage for spruce with its density in the order of o.l+.

The alternate expression c/p has the advantage that it relates directly to two quantities that can be readily determined by the luthier: for a wood strip cut to some standardized dimensions, c is directly proportional to its resonance frequency and p to its weight. It is doubtful whether many makers avail themselves of this quantitative information; the luthier who neglects to determine density may be ignoring its most telltale character. C. M. Hutchins uses a "xylophone" in which a strip of new material can be compared as to its frequency of lowest resonance and weight with various known woods , excellent good and bad, all strips being of a standardized size. One can easily choose standardized dimensions such that frequency and weight give c and p almost directly: thus the lowest frequency in eps from strips ik.k x 1.7-5 x o.l+ cm multiplied by 500 gives c in cm per second, and weight in grams divided by 10 gives density p in grams per cc. From these E can be calculated from the relation, c = (E/p)^. Constants of certain good violin woods are listed in the following table.

Density E E E C C c /p 6 6 L R V R L R L L R dyne/cm2 cm/sec at 1000 gm/cnH x 10-1U x 10-5 x IO"5 eps

A spruce from W. Germany- -0.35 10.2 0.79 12.9 5.1* 1.50 15.1* 0.02 0.01*5 A spruce from Vermont 0.43 12.1 0.91 13.3 5.3 1.1+5 12.3 0.021* 0.053 A "Sitka spruce" o.l+o 10.1* 0.73 11*.2 5.1 1.35 12.7 0.026 0.060 maple from Czecho-Slov. 0.58 7.7 2.00 3.9 3.65 1.85 6.3 0.027 0.051+ 22

The foregoing concerns the "reactive" properties of wood. Of these, there is yet another. E.Skudrzyk has emphasized the probable importance of shear in fiddle material. As frequency is raised a point is reached at which bending gives place to shear as a more important strain than extension. This is evidenced in tests by the fact that frequencies of resonance in the higher modes turn out to be smaller than extrapolation from lower frequencies suggests. Reference may be made to an article by James N. Lange, Jr., for an excellent method of determining the transition point. Though important in the upper octaves of the instrument, the effect of shear in wood is probably small in the lower range. For example, in a cross- grain strip of Sitka spruce 30 cm long and 0.38 cm thick, the separations of adjacent resonances justified expectations on the basis of bending waves up to 1000 eps, but were clearly those of shear waves above I+ooo cps. In between, the transition was gradual.

Lastly, the internal friction in the material must be neither too great nor too small. This may be obtained by standard methods; the duration of tone in the "xylophone" gives a good qualitative indication. If it is too small, as for example in aluminum, response at resonances would be obnoxiously high. If too great, the peaks will be unduly lowered. In wood the effect of excessive internal friction is to increase losses at high frequencies, > thus decreasing brilliance in timbre. If peaks are separated by many semitones, response in the valleys between them is but little affected. When they are close together, as they are likely to be in the upper range, the effect may be considerable. Particularly above I+ooo eps, increased loss is desirable in order to reduce shrillness.

In wood, logarithmic decrement differs in bending along and across the grain, being typically three or four times the greater across. In shear, decrement is about the same as in bending across the grain. All these contribute to the decrement in a complete instrument. In a substitute material it will probably not be necessary to have the identical distribution of decrements that occurs in wood as long as the resultant in the finished instrument is suitable. It might turn out that an artificial material inferior to wood in some ways is superior in others, such as in its resistance to change in humidity. The optimist will hope that it is better in all respects. Summary. Necessary conditions for an artificial material for a violin top are (l) that it be orthotropic, with Young's modulus in principle directions of elasticity in the ratio of about Ik to 1; (2) that its flexural figure of merit (E/p3)^ be 10 x 105 in cgs units or higher, E being taken in direction of greatest stiffness; and (3) that its logarithmic decrements' for flexural vibrations at 1000 eps in strips of top-plate thickness must be in the order of 0.025 and 0.050 for the two principal orientations, or some other pair of values giving the same decrement in a top plate. In a material for the back the figures should approximate, for (l), k to 1, for (2), 5 x 105, and for (3), in the same order as for spruce, or somewhat less, though this is not critical. These figures are somewhat more lenient than those for the best woods.

J. Acoust. Soc. Amer. Vol. 35, No. 3, pp. 378-88 (1963)

ON MAKING A VIOLIN BOW - Maxwell Kimball The first thing that appears when inquiring into bow making is that the violin makers consider it a tricky business, even more exacting than violin making. While most of them are expert at rehairing and repairing bows, only a few make them. The literature on violin making is quite complete and is usually accompanied by para- graphs on bow making. The instruction on bows is generally incomplete and at times questionable.

Though this writing is directed at violin bows, it applies equally well to viola or cello bows or any bow for the violin family of instruments.

# If you have painted, you may have been surprised and delighted at how much more beautiful color you see after becoming color conscious. So when one compares the different qualities of bows played on a good instrument, one becomes conscious that a good bow gives enhanced ease of playing and a clear singing tone quality far beyond that of an ordinary bow. A good bow is as important in its way to an artist as a good instrument; neither complete without the other. The location of the point of balance affects the ability to play fast passages with ease and is so critical that a shift of a tenth of an inch in its location may render a good bow undesirable to an accomplished player. It is quite common when testing a bow to find the location of the point of balance in the wrong place. Still, correct balance is not enough. Good wood in the right proportions shaped with just the right camber is what gives life and clarity of tone. After testing and rejecting all but the best quality wood, we still find that each piece has its different characteristics of elasticity, stiffness and weight to be taken into account in making the adjustments in design, almost too subtle to notice, yet which yield marked changes in tone quality. The differences in tone quality drawn from the same instrument by different bows is one of the most surprising things in connection with this work. Eulogizing Francois Tourte's "Magic Wand" may be inspiring or baffling, but it is not helpful toward telling how to make a bow. So hunt up bows, examine them, and talk about them with the people who own them. Measure and weigh them, and test them to see what they do, and compare one with another, and so become acquainted with what you are trying to make. Bow frogs may be purchased from various companies who supply the violin making trade. A good frog is an artistic and precise piece of machinists! work, and while they are available in good quality, it is not worth while to try to make them. My opinion is that the conservative designs are generally the most artistic and more suitable for the serious player than the elaborate exhibition designs. Frogs vary in size and weight and so should be carefully selected to suit the type and balance of bow desired. The quality of bow wood is of prime importance. To date pernambuco is accepted as the best. Pernambuco is obtainable in staves from suppliers to the violin trade, and in logs from importers of fancy hardwoods. It must be straight-grained and free from knots and worm holes. Staves have to be carefully laid out' on the planks before cutting, to avoid all defects. The wood should be dense and fine grained and especially stiff for its weight. It is very hard and somewhat stringy and will tear up under a plane which is not very sharp. Darkwood of the best quality is hard to find, and wood lighter in color is more desirable when it is harder and stiffer. I have rejected handsome hard wood which was too soft, and with too open a grain. Other pieces though hard and dark and rich looking were rejected as being too heavy for their stiffness like rosewood or ebony. All I can say is to use the best wood available. There is no difficulty about getting design material for a bow head, because bows have been extensively pictured. The stick is cut and shaped straight and afterward bent by hand to the required camber with heat too hot to touch and not hot enough to scorch the wood. The heat should be applied long enough to penetrate into the wood, the requirement varying with the thickness. Whether the bow shaft is round, an octagon, or a fluted octagon makes no difference in the performance and is a matter of choice for appearance.

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In order to understand the shape of the stick, a curve representing the varying thicknesses is helpful. Draw a base line with inches laid out on it representing the length of the bow at a reduced scale. At each inch along the stick measure its diameter and lay out points at ten times these diameters above the corresponding locations on the base line, and connect with a curve. The base line represents the shrunken length of the bow, and the height of the curve above the base line represents the varying thicknesses, which should be measured with, a micrometer and recorded in thousandths of an inch. With a collection of these curves to the same scale on nearly transparent tracing cloth, the bows they represent may be compared by placing their curves over one another. The difference in shape between the best and less desirable are then apparent. This information with points of balance, center of percussion, measured stiffness, and weights, form a fairly complete record of physical characteristics and a basis for bow design. The location of balance point (the center of gravity) is arrived at by bal- ancing the bow over a ridge with the hair drawn up to playing tension, and recording its exact position. The center of percussion— also called the center of gyration or oscillation—is the point at which a baseball batter tries to connect with the ball so that his hands won't sting. If the ball hits the end of the bat, his hand will be pulled forward; if the impact is near his hand it will be pushed backward. There is a point in between where the force tends to be zero. No such simple statement can be made in relation to a violinist holding his bow, for many other considerations come into play, such as the weight of his hand, method of holding the bow, and position of the frog. Such considerations, however, do not alter the fact that the location of the center of percussion (or an equivalent) is necessary in order to complete the statement of the balance of a violin bow. The location of the center of gravity tells something about the bow's response to translation; while the center of percussion tells something about the bow's response to rotation about the hand as center.

A good way to locate the center of percussion of a violin bow, which meets both theoretical and practical considerations, is as follows:

1. Screw the bow up to playing condition. 2. Tie a small but heavy object, such as a large metal nut, to the end of a fine thread. 3. Support the bow and the nut on a thin metal rod as shown in the diagram, so that both can swing freely. The bow should hang so that the curved part of the frog near the point of the thumb acts as the center of rotation. 4. Start the bow and the nut swinging together, adjusting the length of the fine thread until * the pendulum motions of the bow and the nut are exactly synchronized.

5. When this is achieved, the center of the nut locates the center of percussion. Notice that the center of percussion is always with reference to a center of rotation. Thus the center of percussion must change if the center of rotation changes; while the center of gravity of course remains the same. For this reason the positioning of the frog in tightening the bow hair is important, as is the length of the bow hair and the effect of humidity on its stretching characteristics.*

t *Editor's note: A further discussion of the center of percussion can be found in "A College Textbook of Physics" by Arthur L. Kimball, Holt 1923. Since this text is long out of print, the following excerpt is given. It is interesting that the author of this article on violin bows, the late Maxwell Kimball, was the son of Arthur L. Kimball.

"If a rod or pendulum is suspended from an axis A (Fig. 72) and if that axis is given a sudden sidewise impulse or if it is moved rapidly back and forth from side to side, the inertia of the rod will cause it to move as though a certain point B was fixed and the rod turned about that point as axis . "This instantaneous center of the motion is not the center of gravity C, but is the center of oscillation corresponding to the axis of suspension at A. A marble placed on a little shelf at B is scarcely disturbed by the sudden to-and-fro movements of the axis A, while at any other point it would be instantly thrown off.

"On the other hand, when the pendulum suspended from the axis A is hanging at rest, if a sudden sidewise impulse is given to the bar at B, as when it is struck a blow at that point, no sidewise impulse is communicated to Fig. 72 A in consequence, but the bar simply tends to turn

page 97 "College Physics" by A.L.Kimball about Aas an axis. For this reason the point B is also called the center of percussion corresponding to the axis A."

The stiffness of the stick may be obtained by measuring the deflection as follows: Remove the frog and support the stick on two supports - one under the head, and the other at the frog end - a distance of 25V apart. Balance a 200 gram weight on the center of the span. Measure the difference in height of the space under the stick where the weight is placed with the weight on and off, by slipping in a wedge shaped piece of cardboard which has been calibrated to measure in hundredths of an inch. The stiffness of the hair against the strings is measured by tightening the hair until a 0.3" wide strip of cardboard fits between stick and hair at the narrowest point, record the distance of this point to the head end of the bow, and test for stiffness by pulling a small wire stirrup against the hair with a spring letter balance to bring the hair to touch the stick and recording the required pressure in ounces.

25 The bend or camber of the stick is measured with the hair relaxed, it is the greatest distance from the stick to a straight edge placed against the back of the head and frog. Record the distance and the location of the measurement from the point.

Record the length of the bow and its serial number Record the weight in grams, and balance point of the bow without hair and wrapping. Record weight of frog with screw and button. Record weight of finished bow complete. When drawing a design curve to represent the thickness of a new bow, there may be modifications to suit the density of the wood as well as adjustment to give the weight and stiffness characteristics desired. To bring out the best tone from a large new viola one needs a heavier, stiffer bow and quite a different manner of playing than is used when playing a smaller mellow, antique instrument. From accumulated data develop a suitable design curve for the new bow. Cut the stick to agree with the diameters established by the new curve checking constantly with the micrometer aimed at 0.003" oversize to finish on the mark. Then fit and glue on the ivory tip plate and shape the head. Next center the still straight shaft of the bow cut to the right length in the 4 jawed chuck of a machinist's lathe with the end to receive the frog projecting a short distance. Face off the end of the stick at right angles and drill a starting hole with a small "centering drill"; then drill to the required depths the two sizes to suit the screw which draws up the frog. Cut the mortis to suit the eye on the frog as it travels on the screw, limiting the mortis so it will be covered by the frog in all positions. Cut a mortis in the head through the ivory to receive the hair and wedge, and you are ready to bend the stick to the required camber as mentioned above. The shape of the camber of a bow may be a thing of beauty but it also has a definite influence on the stiffness and the pull on the hairs, and consequently on the tone and playing quality of the bow. The result of bending should be tested with hair and frog borrowed from another bow, fitted temporarily with wedge into the head mortis. Correct the camber curve until it is satisfactory and straight when the hair is drawn up to playing tension. Tape on an appropriate weight of solder wire to simulate the weight of wrapping, leather, silver wire, etc., so you can try the bow for tone and feel . The bow now should be carefully smoothed and finished. When the finish is complete the bow will be ready for hair and wrapping. The leather and silver wire or whatever wrapping is selected should be of the right weight so that the location of the resulting balance point is satisfactory. Metal wire wrapping should be done only when the wood is thoroughly dry, at best during the winter months. I will not describe this work as it may be competently done by whoever usually fixes a bridge or rehairs your bow. Hairing a bow is work that takes skill and experience without which a bow can easily be damaged. The problem presented in establishing the quality of the wood, and making adjustments to obtain the best weight, balance, and stiffness to give good performance and tone, and trying to develop beauty of design, material, and workmanship, makes bow design fascinating and bow making artistically rewarding.