Measurement of acoustic power flow in the near-field of a vibrating surface

A technique for measuring the intensity (power flow per unit area) of the acoustic find near the surface of a vibrating body is presented. It is based on the frequency domain characteristics of the joint random process constituted by the surface acceleration and the near-field pressure. The accuracy of this new technique as applied to source sound power estimation is determined on a baffled piston source and compared with the reverberant room method. For the first time, measured patterns of acoustic intensity in the near-field of a vibrating plate are presented. An assessment of the practicality of this technique as a research tool in the study of machinery noise is included.