Environmental acoustic recording system (EARS) buoys for marine animal acoustics.

EARS buoys were developed as autonomous, moored, underwater recording systems by the Naval Oceanographic Office (NAVOCEANO) to make long‐term ocean ambient noise measurements. When the Littoral Acoustic Demonstration Center (LADC) was formed as a consortium of university and U.S. Navy scientists in 2001, the buoys were capable of measuring up to 1000 Hz for 1 yr. LADC added listening to sperm whales to its noise and propagation measurements. NAVOCEANO quickly modified the buoys to measure up to 5859 Hz for 36 days. The buoys, moored at depths from 550 to 950 m in the Gulf of Mexico, produced exceptionally clear recordings of sperm whale echolocation and coda clicks and recordings of other whales. EARS Generation 2 buoys are now capable of recording one channel to 96 kHz, or four channels to 25 kHz, for more than 13 days on four 120 Gbyte notebook disk drives. Experiments in the Gulf of Mexico and the Ligurian Sea have targeted both sperm and beaked whales. Audio results and visualizations of these recordings reveal rich detail of Odontocete clicks and enable new analyses, such as the identification of individual whales from the properties of their clicks. [Research supported by ONR and SPAWAR.]