Bernard E. Richardson
Dept. of Phys. and Astron., Univ. of Wales College of Cardiff, P.O. Box 913, Cardiff CF2 3YB, UK
The acoustical function of the guitar is now reasonably well understood. The various modes of the vibrating string couple to structural and air-cavity modes of the body. These in turn interact with the surrounding air thus enhancing the radiation of energy from the string to the listener. The modal properties of the instrument are thus of central importance in determining its sound quality. It is of great interest to the maker to know how these modal properties might be adjusted to produce instruments of pre-determined sound quality. This paper will give a resume of experimental and theoretical work undertaken at Cardiff to determine formal relationships between physical properties of the instrument (construction and materials) and psychoacoustical evaluation of guitar tones. The aim of this work is not to define parameters of an idealized ``perfect'' instrument---that would be a futile goal. Instead, the aim is to identify those features of construction which have a perceptible effect on the guitar's sound and to define acceptable limits for modal properties. The latter will be discussed theoretically, but taped demonstrations will be presented to emphasize the points being made.