Thomas H. Burns
Graduate Program in Acoust., Penn State Univ., University Park, PA 16804
William Thompson, Jr.
Courtney B. Burroughs
Penn State Univ., University Park, PA 16802
Knowledge of the potential and kinetic energy densities, and the complex intensity vector is needed to characterize an acoustic field. Methods are described to obtain and visualize these quantities. Two independent techniques were combined to determine these acoustic field variables, namely, an acoustic intensity measurement technique and near-field acoustic holography (NAH). In the past, conventional acoustic intensity techniques have been used to estimate radiated power and, more recently, to localize and characterize sources. In this study, an acoustic intensity technique was used to obtain, indirectly, the complex pressure on a hologram plane in the near field of a source from a single broadband intensity measurement. From knowledge of the complex pressure on the hologram plane, the free-field was reconstructed using NAH [Loyau et al., J. Acoust. Soc. Am. 84, 1744--1750 (1988)]. After a brief review of these measurement techniques, various methods of visualizing both the steady-state and time-varying acoustic field variables will be introduced. Particular attention will be given to the complex acoustic intensity vector; the vector properties of this quantity will be exploited to characterize the acoustic field. [Work supported by International Jensen, Inc.]