ABSTRACT
Airborne sound is produced either by vibrating surfaces or due to flow. This chapter talks about the conditions under which a vibrating body can produce sound. Initially, the sound produced by a rigid vibrating piston is considered to define the basic concept of radiation resistance. Later, it is extended to a pulsating sphere. But in practice, most vibrating structures support wave propagation, which makes the prediction of sound from such surfaces difficult. An infinite plate in flexural (bending vibration) is chosen to derive the basic conditions of efficient sound radiation. Finite plates, however, have different sound-radiating characteristics than infinite plates. Noise radiated due to vibration of a plate is of significant practical interest. Although most plates used in the construction of machines are finite plates with boundary conditions, the infinite plate helps in capturing the phenomenon of sound radiation using wave interaction of airborne and structure-borne sound.
