Evaluation of angle-dependent spectral distortion for infinite, planar elastic media via angular spectrum decomposition

Abstract

The angle-dependent spectral distortion for an infinite planar interface (IP-ASD) is examined for the case of fluid–fluid and fluid–solid (elastic) interfaces. The results are based on computation of the angular spectrum (plane wave) decomposition of the acoustic pressure field as radiated by an equivalent image source transducer, for each frequency of interest. The exact incident-angle-dependent reflection coefficient of the interface may thus be used in the computation, versus approximate methods previously required [D. P. Orofino and P. C. Pedersen, J. Acoust. Soc. Am. 92, 2883–2899 (1992)]. Comparisons of the previous approximate IP-ASD results to the current exact results are made. IP-ASD results for elastic parallel plates are also presented for a variety of plate orientations and geometries. For the special case of normal incidence, a comparison of the IP-ASD result to a previously published result is made. The IP-ASD is additionally examined for a reduced subset of plane wave components that approximate the radiated pressure field. The error in the IP-ASD versus the number of plane waves in the subset is discussed.