I. Introduction
This paper deals with the importance of the effects of out-of-plane acoustic propagation with respect to the reliability and performance of inversion procedures typically applied in ocean acoustics (e.g., ocean acoustic tomography or geoacoustic inversions). In particular, we focus on shallow-water environments where the interaction of sound with the ocean bottom dominates acoustic propagation. Realistic shallow-water environments, like those encountered on the continental shelf, rarely present a horizontal bathymetry. Out-of-plane propagation effects, also referred to as 3-D effects, may thus occur from the successive reflections of the sound off the nonhorizontal seabed, during which the acoustic waves are gradually refracted in the horizontal direction [1]–[5].