Sound radiation from plates
This chapter describes sound radiation from plates. Both forced and resonant vibrations are considered, and the application of Rayleigh's method of radiation calculation is demonstrated in the case of radiation from forced bending waves. Forced vibrations are directly due to the surrounding sound field exciting the plate. In contrast, resonant vibrations are the free vibrations caused by reflections of the forced vibrations from the boundaries. The modal density for the plate is especially needed, as this is an important parameter for the statistical energy analysis (SEA). The sound radiation from normal modes in plates has been analysed by Wallace, but here it is sufficient to look at approximate results for a square panel. The chapter also discusses radiation efficiency to study the radiation of finite structures. Radiation efficiency is a measure of the radiated sound power from a source relative to the sound power radiated from an equivalent piston source that generates a plane wave.