Underwater Sound Levels (image) NOAA Fisheries West Coast Region Share Print E-Mail Caption These are predicted 50Hz noise levels at 30 meters depth from August to November 2009. Noise predictions were categorized using an estimate of pre-industrial noise conditions (65dB) and the 10th, 50th, and 90th percentiles of the predictions. These categories corresponded to measurements of shipping traffic volumes: pre-industrial, low (pre-industrial to 10th percentile of predicted noise levels), moderate (10th to 50th percentiles of predicted noise levels), heavy (50th to 90th percentiles of predicted noise levels), and extreme (>90th percentile of predicted noise levels). Credit Redfern et al., Endangered Species Research Usage Restrictions CREDIT: Redfern et al., Endangered Species Research Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.