Three-dimensional acoustic localization in complex marine environments

A three-dimension (3-D) hydrophone array named the Acoustic Telescope has been deployed in the New England Shelfbreak and the New England Seamounts to investigate its application on 3-D acoustic localization in complex marine environments. Sound propagation in these two areas are influenced strongly by out-of-plane reflection, refraction, and scattering off the seabed. Particularly, in the vicinity of a seamount, the flank of the seamount acts as the “seafloor” which may be at an angle with respect to the plane of direct waterborne propagation. The seamount also presents an interesting acoustic boundary/medium, characterized by the presence of slopes, ridges, and heterogeneous sediment coverage. This work presents results of acoustic source localization using the Acoustic Telescope (AT), a 25-element 3-D volumetric array. The relative contribution of in-plane versus out-of-plane acoustic arrivals will be analyzed and utilized for 3-D acoustic localization. Improvements of the signal-to-noise ratio by 3-D array beamforming will also be discussed. Work supported by the Office of Naval Research.