The reflections and refractions of acoustic beams at water sediment interfaces

The interaction of acoustic beams with refracting interfaces is discussed in terms of the relation between the plane wave spectrum of the beam and the plane wave reflection coefficient. In particular, the behaviour of beams generated from conventional broadside apertures and those generated from a volume aperture (parametric array) are compared for interfaces which have a range of critical angles. In both cases, the form of the reflected and refracted beams is determined solely by the interaction of the plane wave spectrum and the reflection or transmission coefficient. For the parametric array considered, the extent and shape of the volume aperture and thus the plane wave spectrum is determined by truncation at the water sediment interface, an effect absent for conventional beams.