Ambient Noise and Marine Mammal Acoustics

Abstract : The Littoral Acoustic Demonstration Center (LADC) is an Office of Naval Research funded consortium of scientists from the University of Southern Mississippi (USM), the University of New Orleans (UNO), the Naval Research Laboratory at Stennis Space Center (NRL-SSC), and the University of Louisiana at Lafayette (ULL). LADC was formed to conduct ambient noise and marine mammal acoustic measurements and analyses. Some of the marine mammal goals are to (1) investigate detection, identification, and tracking using bottom-moored hydrophones; (2) coordinate with scientists making visual observations and other acoustic measurements; and (3) evaluate, and modify if necessary, automatic detection and characterization computer algorithms when applied to marine mammal signals received on bottom-mounted hydrophones. The underlying desire is to provide products that will help to assess the effects of anthropogenic noise on marine mammal behavior and the development of mitigation procedures. Due to recent court rulings, the Navy has become concerned with the possible negative effects of sonar on marine mammals and the development of mitigation procedures. Not only do mitigation procedures have Navy applications, but they also apply to some aspects of commercial or scientific exploration of the oceans. LADC has conducted experiments in the northern Gulf of Mexico and in the Ligurian Sea in cooperation with other organizations. Environmental Acoustic Recording System (EARS) buoys were deployed at sites with historically abundant sightings of marine mammals. EARS buoys are autonomous self-recording, single-channel, bottom-moored acoustic buoys developed by the Naval Oceanographic Office. Analysis approaches have included click production analysis, propagation modeling of sperm whale clicks, and spectral and wavelet transforms of sperm whale clicks.