Dynamical properties of piano soundboards
Résumé
In pianos, the transfer of energy from strings to soundboard and the radiation of sound are highly
dependent on the dynamical properties of the soundboard. In this paper, a numerical study is
conducted for various rib configurations, showing that even slight irregularities in rib spacing can
induce a strong localization of the soundboard velocity pattern. The effective vibrating area can be
further reduced due to the spatial filtering effect of the bridge. Numerical predictions of modal
shapes and operating deflection shapes are confirmed by series of measurements made on upright
piano soundboards. Simulations of radiated pressure based on measured and calculated soundboard
velocity fields show that localization tends to broaden the cone of directivity and to reduce the
number of lobes.