The Technical Guidance provides thresholds for onset of permanent threshold shift (PTS) and temporary threshold shifts (TTS) in marine mammal hearing for all underwater sound sources. It is intended to be used by NOAA analysts and managers, other federal agencies, and other relevant user groups/stakeholders to better predict how a marine mammal’s hearing will respond to sound exposure.
To develop these thresholds, NOAA Fisheries compiled, interpreted, and synthesized best available information on the effects of anthropogenic sound on marine mammals' hearing, as well as developed a method for updating these levels through a systematic, transparent process. The Guidance outlines NOAA Fisheries' acoustic thresholds and describes in detail how the thresholds were developed and how they will be updated in the future.
This document provides voluntary technical guidance for assessing the effects of underwater anthropogenic (human-made) sound on the hearing of marine mammal species under the jurisdiction of the National Marine Fisheries Service (NMFS). Specifically, it identifies the received levels, or thresholds, at which individual marine mammals are predicted to experience changes in their hearing sensitivity (either temporary or permanent) for acute, incidental exposure to underwater anthropogenic sound sources.
The following Tables and Figures summarize the three main aspects of the Technical Guidance: 1) Marine mammal hearing groups (Table ES1); 2) Marine mammal auditory weighting functions (Figures ES1 and ES2; Table ES2); and PTS onset thresholds (Table ES3).
National Marine Fisheries Service (2018). 2018 Revisions to: Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0): Underwater Thresholds for Onset of Permanent and Temporary Threshold Shifts. Report by National Oceanic and Atmospheric Administration (NOAA), US Department of Commerce (DOC), and National Marine Fisheries Service (NMFS). pp 178. https://tethys.pnnl.gov/publications/2018-revisions-technical-guidance-assessing-effects-anthropogenic-sound-marine-mammal