Obtaining baseline measurements of ocean ambient sound at a mobile test berth site for wave energy conversion off the central Oregon coast

A year-long experiment to monitor underwater ambient noise measurements in shallow, (~50m) open water along an energetic coastline in the Pacific Northwest (USA) was conducted. Bottom mounted passive acoustic recorders were deployed in March 2010 by Oregon State University (OSU) and NOAA/Pacific Marine Environmental Laboratory's Marine Acoustics Research Group in an area designated by the Northwest National Marine Renewable Energy Center (NNMREC) as a mobile ocean test berth (MOTB) site for wave energy conversion (WEC) platforms off the central coast of Oregon. Acoustic recording packages recorded continuous (1 Hz-2 kHz) sampling at two offshore locations near and within the MOTB. Maximum and minimum total sound pressure levels recorded during the experiment reached 136 dB re 1 μPa and 95 dB re 1 μPa respectively. Meanwhile, the time averaged sound pressure levels for the year long deployment were 113 dB re 1μPa. These data provide the initial baseline recordings required for a meaningful assessment of the shallow water ambient noise levels in the Oregon nearshore coastal environment prior to the installation and operation of wave energy conversion devices.