Air and structural modes of a harpsichord

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 J₀ 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.