Abstract:

The role of the lowest frequency reed resonance in sound production by single reed instruments has been well established [S. C. Thompson, J. Acoust. Soc. Am. 66, 1299--1307 (1979)]. However, the acoustical significance of the reed's higher vibrational modes remains an open question. Recently, several higher frequency modes have been identified for a clarinet reed [P. L. Hoekje and G. Matthew Roberts, J. Acoust. Soc. Am. 99, 2462(A) (1996)]. The present study examines several reeds and extends Hoekje's results to higher frequencies. Holographic interferometry was used to locate the frequencies and to image the vibrational patterns of higher vibrational modes of three nominally equivalent commercial clarinet reeds. Dry reeds were clamped to a specially designed reed holder allowing the reeds to vibrate freely when driven by an acoustic sound field. In all, six or seven distinct modes with frequencies below 7.5 kHz were located on each of the three reeds. Four of the modes (including the fundamental) appear to be similar to the one-dimensional modes of a cantilevered beam. The other three modes show two-dimensional vibrations indicating twisting motion. Variations in modal frequencies among the three reeds studied range from 3%--12% over the different modes.