Range-Depth Tracking of Sounds from a Single-Point Deployment by Exploiting the Deep-Water Sound Speed Minimum

• Main Authors: Thode, Aaron, Jan Straley
• Other Authors: CALIFORNIA UNIV REGENTS LA JOLLA CA SCRIPPS INST OF OCEANOGRAPHY
• Format: Text
• Language: English
• Published: 2014
• Subjects: Biological Oceanography; Acoustic Detection and Detectors; Acoustics; *CETACEA; *UNDERWATER ACOUSTICS; ACCURACY; ACOUSTIC VELOCITY; ALGORITHMS; ARRAYS; DEEP WATER; DEPTH; GLIDERS; HYDROPHONES; RANGE(DISTANCE); RAY TRACING; SOUND; TRACKING; RANGE-DEPTH TRACKING; SINGLE-POINT DEPLOYMENT; DEEP-WATER SOUND SPEED MINIMUM; LOCALIZATION; HUMPBACK WHALE CALLS; Water Sound; Humpback Whale; Alaska
• Online Access: http://www.dtic.mil/docs/citations/ADA617864; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA617864

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. Prepared in collaboration with the University of Alaska Southeast, Sitka.