1. A loudspeaker adapted for operation over an operative frequency range, comprising: a member extending transversely of its thickness and capable of sustaining bending waves over an active area of the transverse extent of the member, the member having physical parameters of geometry, bending stiffness, areal mass distribution and damping, the values of which affect the distribution of resonant modes of bending wave vibration over the active area of the member, said parameters having selected values such that the resonant bending wave modes are beneficially distributed in frequency over the active area of the member, and a transducer coupled to the member in a region of the active area of the member where a plurality of lower frequency resonant bending wave modes in the operative frequency range have vibrationally active anti-nodes so that the transducer will couple with the lower frequency bending wave modes.