Experimental analysis of the vibroacoustics of a trombone bell
Résumé
The influence of wall vibrations on the sound produced by a wind instrument has engendered a long-lasting debate among scientists, musicians, and instrument makers. The vibrations of a sounding wind instrument can clearly be felt and measured but the influence of these vibrations on the radiated sound is more difficult to bring to light, because the fluid-structure couplings involved are particularly weak excepted when coincidence effects occur. The case of the trombone bell is particular because this part of the instrument is large and thin, which favours vibrations of large amplitudes. An experimental study has been performed using a tank of water in which the studied trombone is placed. The tank can be filled with water in order to modify the mechanical modes of the system in a continuous manner. Such an experiment is designed from the historical experiment made by D. C. Miller one century ago for studying the acoustics of vibrating organ pipes (Science 29 (735), 161171, 1909). The acoustic impedance and mechanical responses of a trombone bell excited by a loudspeaker or an impact hammer are measured for different levels of water permitting a fine analysis of the vibroacoustics couplings.
Domaines
Acoustique [physics.class-ph]
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