The response to sound and consequent sound radiation (“radiation scattering”) for one linear resonant mode of a part of a larger structure are analyzed for a general structure. A modal reciprocity relation is established between modal radiation resistance and the transfer function which relates incident sound pressure to modal (“generalized”) force in the absence of motion. Response and resonant scattering are also analyzed for excitation by noise. When all angles of incidence are equally probable, the means‐quare response velocity is inversely proportional to modal stiffness and proportional to the fraction of total damping attributable to radiation; it is independent of all other characteristics of the structure.