Modal analysis of violin bodies viewed as three-dimensional structures

Modal analyses of violins show several strong modes in the low frequency range. Holographic interferograms suggest that four strong modes can be interpreted as doublets having two and three nodal planes that intersect a cylinder with a roughly elliptical cross section at the bridge [A. Runnemalm, N.-E. Molin, and E. Jansson, J. Acoust. Soc. Am. 107, 3452–3459 (2000); M. Roberts and T. D. Rossing, Catgut Acoust. Soc. J. 3, 9–15 (1998)]. This is especially clear when the instrument is viewed simultaneously from three sides using mirrors, and the holographic system is made sensitive to in-plane motion as well. These doublets are not unlike those observed in cylindrical vibrators such as bells, and they remind us that a violin is a 3-dimensional object.