Coherent reflection of an acoustic plane wave from rough interfaces in a horizontally-stratified medium, within which the sound-speed distribution subject to a small and random perturbation, is considered in this paper. The general formulation based upon the theory for rough-interface scattering in a stratified medium, in conjunction with that for random medium is derived. The Green’s function for a random medium bounded by two surfaces, which serves as generic solution of the problem, is obtained. The formulation is then applied to a simplified seabed environment to study the effects of surface roughness and medium inhomogenieties on the coherent reflection. The numerical results demonstrate that both the rough-surface scattering and medium scattering distract the energy from the coherent field, making the coefficient of the coherent reflection reduced with an amount, depending upon the degree of roughness and randomness measured by the relevant parameters. Furthermore, the characteristics of the distribution for the reflection coefficient with respect to incident angle show distinct feature, potentially allowing identification of dominant scattering mechanism.

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