Tone quality and important modal properties of the guitar
Howard A. K. Wright · The Journal of the Acoustical Society of America · 1999
The main function of a string instrument’s body is to convert string vibrations into radiated sound that is detected by the listener. The coupling between string and body modes determines the vibrational response of the instrument to a plucking/bowing force applied to the string, and therefore has a crucial influence on the instrument’s sound. The nature of this coupling depends on the body’s modal properties as detected at the bridge. An interesting question arises: how do changes to the body modes affect the perceived tone quality of the instrument? The use of numerical models permits independent control of an instrument’s modal properties. By performing psychoacoustical tests with sounds synthesized from these models one can examine the effect on perceived tone of changes to individual body modes. In relation to the guitar, this approach has shown that mode shapes, and, in particular, the positions of nodal lines in relation to the bridge, have a powerful influence on tone quality. This paper reviews the current understanding of the links between the guitar’s modal properties and its sound, and highlights the need for further numerical and psychoacoustical work as a means of extending our knowledge in this area.