The Science of Musical Sound by William Ralph Bennett Jr

Author:William Ralph Bennett Jr.
Language: eng
Format: epub
ISBN: 9783319927961
Publisher: Springer International Publishing

Various resonances in bowed string instruments were studied in some detail for a Stradivarius violin and several other instruments by Carleen Hutchins (1962, 1981, 1983). Of the several wood resonances, the one just below the open A string on a good instrument seemed to be most important in evaluating an instrument. On bad instruments, that resonance either didn’t exist, or was above the A string. The other main wood resonance on the Stradivarius fell just above the open G string. A strong (Helmholtz) air resonance is also important and typically occurs just below the open D string on a Stradivarius violin. Sacconi’s (2000) observations on air resonances in violins by Stradivari discussed above were in reasonable agreement with Hutchins’ conclusions.

In doing this work, Hutchins speculated that to make a powerful viola, cello, or double bass, one ought to reduce the arching of the top plate and increase its area and to scale each instrument in such a way as to make the principal wood and air resonances fall below and above the two middle strings as in the better Stradivari violins. The reduced arching of the top plate was to increase the projection of sound from the instrument. To get the right volume with reduced rib height, greater length was required for the sound box. For violas and cellos this scaling process meant enlarging the dimensions of the new instruments. One had to change the length of the wood box so that the first excited air mode and a wood resonance fell above the open-string resonance for the third string and to adjust the volume (shape and rib height) so that the “Helmholtz” air resonance fell below that for the open second string. The wood resonances of course depend on the thickness and size of the top and bottom plates—not to mention the acoustic properties of the wood itself.

One problem with the Hutchins approach is that her new viola is about the same size as a cello, and her new cello is about the size of a normal double bass. By the time you get to the new double bass, it takes on proportions mildly reminiscent of the Vuillaume octobass. Hutchins designed and made an entire octet of such scaled instruments that had remarkable power and great beauty. (See Fig. 5.43.) I measured the sound output of several of these instruments. Most were well-above 95 dB at 1-m and the new double bass peaked at over 105 dB at a distance of 3 ft. That is nearly the sound level obtained from the entire double bass section of a large symphony orchestra. Hutchins’ double bass was at least playable by a tall person standing on the floor.

Fig. 5.43The Hutchins Octet (photographed by John Castronovo in the living room of Carleen Hutchins and reproduced here by her permission)

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