CAS Journal
May 1997
Volume 3, No. 3 (Series II)

From the Editor ...

I am pleased to welcome Professor Robert T. Schumacher to the CAS Editorial Board as Associate Editor for Musical Acoustics. Bob will be responsible for the review process of papers relating to musical acoustices in the Journal. A thorough review process is key to maintaining and even enhancing the quality of the Journal's contents, and Bob is exceptionally well-qualified to direct this function. As we note on page 49, this year he marks his 25th anniversary as a CAS member. A Professor of Physics at Carnegie-Mellon University since 1957, he has researched and written extensively on violin acoustics. Readers of this Journal will recall his paper (with S. Garoff) "Bowing with a Glass Bow," in the November 1996 issue, with the remarkable images of the slip-stick bowed-string motion at the point of contact between bow and string. A number of his papers are included in the recent publication, Research Papers in Violin Acoustics 1975-1993, edited by Carleen Hutchins and Virginia Benade. (Look for the review by Neville Fletcher in this issue of the Journal.) A violinist, Professor Schumacher plays a violin made for him by Curtin & Alf (also CAS members).

Some readers have wondered about the section of the Journal designated "Violinmaker's Forum." We have used this designation to flag papers that should be of particular interest to practicing luthiers. Papers in this section may focus on using acoustical principals and research findings in the process of instrument making and may be somewhat less technical. Some papers will describe tools, jigs, and techniques that facilitate good construction. As we have said before, good craftsmanship is essential if instruments are to embody advances in knowledge of violin acoustics.

It may be important to know that all papers in the Journal pass through a formal process of written reviews by anonymous reviewers. Associate Editor John Randerson of Colorado Strings manages the review process for many of the papers that appear in the "Forum" section. In addition to working in his shop, John has written for this Journal and the Strad and is collaborating with Karl Roy on a book on violinmaking.

I encourage you to read the announcement on page 52 for ISMA '98: Tone and Technology in Musical Acoustics to be held near Seattle, Washington in June 1998. Planning is underway, and the organizing committee would appreciate hearing from persons who want to participate or attend.

As always, we appreciate your feedback about the Journal so that it can be improved and better meet the members' needs.

Good reading!

A. Thomas King

Table of Contents with Abstracts

2 - The Helmholtz Resonance and Higher Air Modes of the Harp Soundbox by Alexander J. Bell

The air modes of a rigid soundbox of the Salvi "Orchestra" Concert Harp are analysed. A Helmholtzian mode is modelled using an elliptical approximation. The resonant frequencies and profiles of the air modes are affected by the apertures in the rear and base of the soundbox.

9 - On Body Resonances C3 and Violin Construction by Erik V. Jansson, Benedykt K. Niewczyk, and Lars Fryden

Previously, high quality, soloist violins have been found to have a prominent resonance peak between 500 and 600 Hz. The authors look for answers to two questions related to this peak: is the soundpost placed on a nodal line in order not to dampen the resonance and is the resonance made prominent by the design of plates and of ribs? With a small weight fixed to different positions of the experimental violin it is shown that maximum sensitivity is found at the upper and lower end blocks and at the c-bouts. The result indicates that clamping the chinrest beside the lower block is acoustically favourable and that the resonance is affected by the neck. In answer to the two questions, the experiments indicate that the soundpost normally is close to but not on a nodal line and the peak level can be affected by the soundpost. For the C3 resonance the back plate seems to be more important than the top plate.

15 - The Reciprocal Bow as a Workshop Tool by Joseph Curtin

Good violinists impose their own sound on violins. Are they the best people to evaluate them? Playing a violin "backwards" may be the most objective way to test it.

19 - Effect of Sound Post Adjustment by Oliver Rodgers

Harmonic analyses were made of the glissando tones of a violin when the sound post was adjusted in two steps from a position which favored the higher strings to one which was judged to be slightly favoring the lower strings. In the final sound post position a prominent resonance appeared at about 930 Hz, the nodal pattern of which is given. A plausible explanation is offered for its appearance and its effect on the overall tone of the instrument.

25 - Acoustic Conditions for a Soloist's Concert Violin by Hajo G. Meyer

The author formulates and dicusses six conditions, which must be fulfilled in order for a new violin to be suitable as a soloist's concert instrument. These conditions are: projection, dynamic range, tone quality, articulation, vibrato, and ease of playing. Where possible a link is made to the physics of the violin and/or to the practice of the maker.

Violinmaker's Forum

29 -Down-home Lutherie: a Simple Technique for Measuring Loudness by Carolyn W. Field and Frank H. Field

The authors describe a useful method for making quantitative measurements of the loudness of bowed stringed instruments using only simple equipment. Using repeated measurements they conservatively estimate that the reproducibility of the method is better than 10%. They report interesting subjective perceptions of loudness in the course of the work. They find that subjective loudness perception is oftentimes a non-linear function of the pressure amplitude incident upon the ear, and this finding is in accordance with known aspects of the physiology of human hearing. The perceived ability of a stringed instrument to project sound may involve the non-linearity of the hearing function in addition to the physics of the projecting instrument.

37 - Acoustic Experiments with the Violin by Robert T. Jones

In these experiments a small electromagnet transducer is arranged to drive the violin bridge laterally, in the direction of string motion. The transducer is activated by an oscillating voltage of varying frequency and the resulting sound is measured by a sound level meter. The oscillating voltage input is generated by a Macintosh computer which also records the sound level and plots the result as amplitude vs. frequency.

The results are used to characterize the frequency response of good and bad violins, to demonstrate the influence of the sound post and to show the effects of bridge compliance. Vibration patterns (Chladni patterns) of violin plates are shown and are used to explain the directional properties of violin tones. The paper includes the computer program used to generate the results.

42 - New Versus Old: Playing-in Instruments through Vibratory Transmission of Music to the Bridge by Daniel Ling and Mead Killion

The authors vibrated several violins and a viola for 500 hours, by attaching a device to the gridges and playing an FM classical music station through it. Most players and listeners noted tonal changes and thought the changes were improvements.

45 - Use of a Bent Top to Reduce Long-term Violin Deformation by Charles W. Gadd

Using a bent violin top greatly reduced the tendency for string tension to cause the neck to angle upward, the mid-upper region of the top plate to fall, and the upper end of the fingerboard to droop. A separate five-year study implies that a bent top should be significantly less subject to creep - the slow plastic deformation of a material under continuous loading - because of the lesser amount of grain runout.

48 - Paillette Indicators: an Alternative to the Blister Cup Indicators by Ake Ekwall

The author describes an improvement to a device for finding various resonance modes for the violin body.

News and Correspondence

49 -

Recent Publications of CAS Members

51 -

In Memoriam

51 -

Meetings, Workshops, Seminars

52 -

Book Review

56 -

Letters to the Editor

58 -


60 -

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