LONG-TERM GOALS

The long-term goal of this work is to develop techniques for tracking marine mammal sounds in range and depth from a single mooring or platform (e.g. glider), by exploiting the propagation effects of the deep-water sound speed channel. Most listening platforms currently use a single hydrophone to detect events, making no effort at localization. For beaked whales (which have a limited detection range of about 5-7 km), detection may be sufficient to determine whether an animal is close to potential naval operations, but for most species, one needs to assume a typical source level (or source level distribution) to translate a detection's received level into a distance, a risky assumption that generates large uncertainties in position, which in turn degrades attempts at acoustic density estimation and makes mitigation decisions problematic. The range of a marine mammal sound from a compact platform can also be obtained by detecting the same event across multiple platforms; however, for logistic reasons it is highly desirable to investigate avenues for permitting relatively accurate localization from a single platform. OBJECTIVES The primary objective of the work is to estimate the range and depth of cetacean calls using short-aperture vertical arrays, by measuring the vertical arrival angles of various refracted and bottom