Measurements of newly defined intensimetric quantities and their physical interpretation

This paper deals with the measurement and physical interpretation of the quantities a and r introduced in a previous paper @D. Stanzial, N. Prodi, and G. Schiffrer, ''Reactive intensity for general fields and energy polarization,'' J. Acoust. Soc. Am. 99, 1868-1876 ~1996!#. The quantity a, which has the same time dependence as the squared acoustic pressure and the same direction as the time averaged sound intensity ^j&, will be called here ''radiating'' intensity, while r which has zero average, will be called ''oscillating'' intensity. A coherent picture of the energy transfer process in steady sound fields based on the decomposition j5a1r of the instantaneous sound intensity will be sketched and discussed. Furthermore, a direct experimental comparison between a and r and the real and imaginary parts of the complex intensity is presented for some field conditions. © 1997 Acoustical Society of America.