A full-field scattering coefficient for rough interfaces and a modified sonar equation for long-range reverberation

Abstract

A full-field perturbation approach [A.N. Ivakin (2016), J. Acoust. Soc. Am., 140(1), 657–665] allows modifying two terms of sonar equation for reverberation in complex environments and waveguides with rough interfaces. The first one describes a two-way transmission loss for the full-field intensity in the vicinity of the interface. The second term is a full-field scattering coefficient related to but different from the conventional scattering cross-section per unit area. In particular, the coefficient has a non-zero limit value at small grazing angles of incident and scattered waves defined by the contrast of acoustic parameters at the interface and the power spectrum of roughness. The modified sonar equation allows extremely fast estimating the long-range reverberation based on only one (central) frequency calculation of the transmission loss averaged over a certain span of ranges defined by the used frequency bandwidth, and only one value of the scattering coefficient (at zero grazing angles). No multip...