CAS Journal
November 1999
Volume 3, No. 8 (Series II)

To Our Readers

I am delighted to let you know that Dr. Uwe Hansen will assume the responsibilities of Editor of the CAS Journal, starting with the May 2000 issue. Uwe is well known to many of you, not least because of his many years as Chairman of the Musical Acoustics Section of the Acoustical Society of America. He retired recently as Professor of Physics at Indiana State University.

In addition, we have two new Associate Editors. Dr. Evan Davis will head up the Guitar Section in an effort to develop a sustained focus on plucked instruments. Virginia Benade will be the coordinating point for Retrospectives: a series of papers that review what is known today and, by implication, what is yet to be learned about specific aspects of the acoustics of stringed instruments; articles will start appearing some 12-18 months from now.

Together with Gregg Alf and Bob Schumacher we now have a strong editorial team. Moreover, they can count on the active support of the Contributing Editors, a newly established group of scientists and practitioners who will keep the Journal in touch with actuality in the world of musical acoustics; their names are listed on the next page. All of us are indebted to these individuals for their willingness to maintain the excellence of the CAS Journal.

Organizational changes are also taking place in the administration of the Catgut Acoustical Society. After 34 years of unstinting service as CAS Executive Secretary and CAS Journal Managing Director, Elizabeth McGilvray is bowing out. This issue pays tribute to her, but we encourage those of you who have fond memories of working with Elizabeth to write her a note, c/o the CAS Office. Elizabeth will be succeeded by Deana Campion, who has been a Board member for many years. Furthermore, in view of the increasing demands placed on the CAS organization by the Violin Octet, the decision has been taken to establish a separate non-profit organization fully dedicated to Octet support. For further details and background, please read the letter from Julius VandeKopple, CAS President, and the opening note from Garleen Hutchins in the Octet News.

In the back of this issue you will find a comprehensive list of organizations active in the field of musical acoustics, together with a worldwide schedule of relevant meetings. Our intent is to foster communication and participation. We have posted both lists on our Website ( and would be grateful for suggested corrections or additions.

J. Maurits Hudig

Table of Contents with Abstracts

3 - Spherical Radiation from Stringed Instruments: Measured, Modeled, and Reproduced by Perry R. Cook & Daniel Trueman

Directional impulse responses were collected for six stringed instruments, including two classical acoustic guitars, an archiop jazz acoustic/electric guitar, a mandolin, a violin, and a Hardanger (Norwegian folk) fiddle. Impu1se responses were recorded simultaneously from 12 microphones spaced uniformly at the vertices of an icosahedron. Data was collected for all instruments with a human player holding the instrument, and for some instruments also with the instrument suspended without being held by the player. For one guitar, the violin, and the mandolin, the position was adjusted by small angles, and a total of 72 impulse responses (six sets of 12 microphones) were collected. Various signal processing techniques were used to investigate, factor, store, and implement the collected impulse responses. A software workbench was created which allows virtual microphones to be placed around a virtual instrument, and then allows signals to be processed through the resulting derived transfer functions. Signal sources for the application include plucked and bowed string physical synthesis models, or any external sound source. Instrument body transfer characteristics can be parametrically edited, adjusting body size, main resonances, etc. Applications of the database and application software have included adding directional radiation models to physical models for virtual reality and composition, and adding more realistic body resonances to electronic stringed instruments for real-time performance.

15 - On the Function of the Violin Bass Bar by Oliver E. Rodgers

The bassbar is one the least studied and least understood components of a violin. A review of work done, mostly by the author, relating to bassbar function and design is presented. One conclusion is that the standard traditional design is probably heavier than it needs to be. Additional wood should be removed. An additional conclusion is that the asymmetrical location of the bassbar is critical to sound production and asymmetry should be fully exploited in detailed adjusting of bassbar height and plate thicknesses both before and after assembly.

19 - Modal Analysis of Assembled String Instruments: The VIOCADEAS Project - A Progress Report by George Bissinger

Substantial progress has been made on VIOCADEAS (VIOlin Computer Aided Design Engineering Analysis System), an integrated experimental project whose goal is to characterize assembled violins and substructures by their normal mode properties and geometry, and to extract the elastic moduli, density, and damping of their materials not only for computer-modeling of structural dynamics and acoustic output, but also as a guide to material selection. As part of the project a dedicated experimental facility - anechoic chamber, fixed force-hammer excitation - scanning laser vibrometer modal analysis, simultaneous multi-microphone acoustic analysis in the far-field using a rotating microphone array - has been constructed. Operation and finalization of the entire system, including the CT-scan-generated solid model, is expected by the end of the year, after which initial databasing will start.

24 - Analysis of Guitar Tones for Various Structural Configurations of the Instrument by A. Chaigne & M. Rosen

This article is concerned with the particular problems raised by a guitar maker who wishes to make objective analyses of the differences in tonal "power" perceived by the player or audience, for various structural configurations of the same instrument. These structural differences, in comparison with what is widely viewed as a standard construction, correspond respectively to the addition of a soundpost between the top and back plates, to the opening of a second soundhole in the ribs of the instrument, and to the attachment of the strings to an interior neck which is not connected to the top plate.

In order to compare the diverse configurations, two approaches were tried. Measurements of the waveforms were made, first of all, for individual notes using a mechanical method of string excitation, which allows excellent reproducibility of the release conditions of the string. At a separate time, recordings of musical sequences were made for each type of guitar. In order to account objectively for long-term perceptions, the sequences were analyzed in the frequency domain for a duration of several seconds. This study was complemented with time domain analsysis of the initial level of the note and the rate of decay of the free vibration, for the mechanical pluck. when the reference configuration is modified by one of the three changes outlined above. Measures of the strength and directiiity of the radiated sound energy, in relation to the second soundhole case, completed the experimental study.

32 - Rustle as an Attribute of Timbre of Stationary Violin Tones by Jan Stepanek and Zdenek Otcenasek

During listening tests respondents were asked to describe in words the timbre of stationary violin tones of five different notes. A very high frequency of occurrence of the word 'rustle' ('sustivy' in Czech) was found for the highest tested D6 note. A significant positive correlation was found between frequencies of occurrence of the word 'rustle' and levels a) in third-octave bands below the fundamental frequency and b) higher harmonic components. The substantial influence of the spectral component below the fundamental on the perception of 'rustle' was verified by subsequent listening to the original and by filtering modified tones. The spectral component responsible for 'rustle' originated in the neighbourhood of violin body resonance modes A0, T1, and C3. The mean SPL of these spectral components is the only quantity able to distinguish tones with different magnitude of 'rustle'.

39 - Guitar Acoustics and the Catgut Acoustical Society by Evan B. Davis

The mission of the Catgut Acoustical Society (CAS) is "to increase and diffuse the knowledge of musical acoustics and to promote construction of fine stringed instruments". The origins of the CAS are strongly rooted in the study of the violin, but discussions on the acoustics of the guitar have appeared in the Newsletter and Journal from very early on (Newsletter no. 11). As the first Associate Editor for guitar acoustics, I felt it would be appropriate to review the past contributions by our members to the study of guitar acoustics. This overview is not intended to be a scholarly review of the literature (a paper I would love to see published in our Journal) but is a status report on our collective efforts to help pursue the Catgut Acoustical Society's mission.

The Editorial Team

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Tribute to Elizabeth McGilvray

4 - Retirement as CAS Executive Secretary and CAS Journal Managing Director from 1965 to 1999

Letter from the President

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Octet News

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Recent Publications of CAS Members

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Meetings, Workshops, Seminars

47 - ISMA 2001
49 - Future Meetings
50 - Past Meetings

Links to Other Organizations

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