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

Abstract

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.