Modal analysis of a Korean bell.

Large temple bells have been cast in Korea for more than 1200 yr. Most Korean bells have a circular area, called a dang jwa, which provides a convenient striking point, and a sound pipe, called a eumtong, at the top. The asymmetry due to the dang jwa and the ornamentation gives rise to mode doublets and results in a slow beating, which is carefully controlled and considered to be an important characteristic of Korean bell sound. The vibrational modes of a small Korean bell have been studied, using holographic interferometry and modal analysis with impact excitation. The vibrational modes are somewhat different from those of carillon bells, tuned church bells, and handbells previously studied [see N. H. Fletcher and T. D. Rossing, The Physics of Musical Instruments (Springer‐Verlag, New York, 1991), Chap. 21]. No (m,l*) modes are observed. Mode doublet splittings range from 1% to 9%. The fundamental (2,0) mode decays much more slowly than the higher modes of vibration, and thus determines the pitch of the bell. [A.P.’s visit was supported by a grant from Ecole Nationale Superieure des Telecommunications.] ^a)Student intern from Ecole Nationale Superieure des Telecommunications, Paris.