Abstract:

Autonomous acoustic recorders permit full-time environmental monitoring for extended periods. The device described here has been used on the ocean bottom in depths to 44 m. It uses a 4-Gbyte disk to record sounds sampled continuously at 1 kHz (500-Hz bandwidth) except that for 1 min every 14 m 24 s the sample rate is doubled. The lower sample rate is for monitoring the sounds of seismic surveys (airgun pulses) and bowhead whale calls. The higher sample rate is for ambient noise analysis. Capacity is adequate for 24 days. Retrieval is by grappling and has been used on 100 units that operated for 15 days in the Alaskan Beaufort Sea during September 1996. [Work supported by BP Exploration (Alaska), Inc.]