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The acoustical behavior of a harpsichord modeled after 17th-century Flemish prototypes was studied using both experimental and analytical techniques. The vibrational modes of its enclosed air volume were measured and found to correspond closely to those predicted by the Jo and J9 solutions to the Bessel equation for a wedge shaped space. A modal analysis of the complete harpsichord revealed that the soundboard has 36 vibrational modes over a frequency range of 0 to 600 Hz, and that there are numerous modes where the instrument's case has a significant amplitude of motion. Additional information is reported showing that the acoustic output of the harpsichord is reasonably flat over a frequency range of 50-2000 Hz. It is concluded that the resonance behavior of both the soundboard and the enclosed air are important to the tone quality of the harpsichord, and that its generally uniform acoustic output results from the excitation of a large number of wood and air modes by the string partials. PACS numbers: 43.75.Mn, 43.75.Gh LIST OF SYMBOLS co circular frequency, radians • viscous damping factor c velocity of sound, m/s A wavelength, m •p, eigenfunction (mode shape coefficient), air •w eigenfunction (mode shape coefficient), soundboard

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The modal behavior of the harpsichord in the acoustics laboratory at the University of Iowa was determined by percussing approximately 600 points on the external surfaces of the instrument with an instrumented hammer. Both the input from the hammer and the response of the harpsichord were recorded. The data were digitized and the response of each tapped point was converted to a numerical value. These data have been processed into a computer-generated, three-dimensional video tape showing the harpsichord's vibrating modes from 0–500 Hz. Of particular interest is the way in which all the external structural elements of the harpsichord can be shown to vibrate at some point. The results of this work agree closely with the published [E. L. Kottick, Galpin Soc. J. 48, 55–77 (1985)] and unpublished data developed by the authors of this paper.