Scattering of Evanescent Acoustic Waves by Regular and Irregular Objects

摘要

Sound incident on the sea bottom at small grazing angles can produce acoustical evanescent waves in the sediment. The objective of this project was to describe the scattering by regular and irregular objects illuminated by acoustical evanescent waves in a simulated sediment. The theoretical developments were tested with laboratory scale experiments using a unique facility. The observables of interest in the scattering included (but were not limited to): (1) the scattering amplitude as a function of target depth and orientation; (2) the timing of the scattered signals; (3) the frequency dependence of the scattering. Objects investigated included objects having narrow resonances. The results should be helpful in selecting filters to optimize the signal-to-reverberation-ratio for targets buried in real environments and to reduce the rate of false alarms.