Thoughts on Soundboard Vibration

by Paul Wyszkowski

Originally published as Guild of American Luthiers Data Sheet #200, 1981



The classic guitar, like the harp but unlike the violin, the mandolin or the zither, has its strings attached directly to the soundboard. In the case of a violin, it is pretty clear that the bridge communicates primarily vibrations which are perpendicular to the surface of the soundboard. But it is not so obvious how the strings of a guitar transmit their vibration to the soundboard. However, a few minutes’ thought and a simple experiment can settle that question.

Back in 1954, J.K. Sutcliffe stated in an article in Guitar News that the fundamental action linking the string to the soundboard is the rocking of the bridge in response to the longitudinal (along the length) vibrations of the string. That is, the front and back edges of the bridge rise and fall as the string becomes tighter and looser (see Fig. 1). Later, Michael Kasha used this idea in his theory of guitar design. As a consequence, this view was accepted by many luthiers as correct.