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Marine Mammal Acoustic Technical Guidance

2016 Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammal Hearing
(NOAA Technical Memorandum NMFS-OPR-55)

Purpose of the Technical Guidance

The Technical Guidance provides acoustic thresholds for onset of permanent threshold shift (PTS) and temporary threshold shifts (TTS) in marine mammal hearing for all 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 acoustic 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 document outlines NOAA Fisheries' updated acoustic thresholds and describes in detail how the thresholds were developed and how they will be updated in the future.

Due to the complexity and variability of marine mammal behavioral responses, NOAA will continue to work over the next years on developing additional guidance regarding the effects of anthropogenic sound on marine mammal behavior.

2017 Presidential Executive Order (EO) 13795, Implementing an America-First Offshore Energy Strategy

Section 10 of the Presidential Executive Order 13795, Implementing an America-First Offshore Energy Strategy (April 28, 2017) calls for a review of the 2016 Technical Guidance. To assist the Secretary of Commerce in his review under EO 13795, we conducted a comment period on the Technical Guidance.

The public comment period lasted 45-days and ended on July 17, 2017. We advised the public to  focus comments on those relating to the purpose of the review of the Technical Guidance under section 10 of EO 13795. For example, we welcome comments on two particular aspects of the Technical Guidance:

  1. Peer-reviewed scientific literature: information regarding the availability of published new science relevant to marine mammal hearing or impacts of noise on hearing since the publication of the Technical Guidance and  suggestions for how to consider new information within the Technical Guidance.

  2. Implementation support: recommendations regarding how NOAA Fisheries can further aid in the application and implementation of the Technical Guidance (based on difficulties encountered and/or ways NOAA Fisheries can facilitate and/or improve implementation for action proponents).

Process to Develop Technical Guidance

The Technical Guidance has undergone an internal review, three external peer reviews, as well as a follow-up peer review, three public comment periods, and received informal input from key federal partners

External Peer Reviews

The first external peer review, which was completed September 2013, focused on the scientific and technical studies used in the analysis for the development of proposed onset PTS and TTS acoustic thresholds. (Report link)

The second external peer review evaluated a U.S. Navy Technical paper provided to NOAA in January 2015 as part of the Navy's Phase 3 Acoustic Effects Analysis. The paper describes the Navy's proposed methodology for updating auditory weighting functions and subsequent numeric thresholds for predicting auditory effects (TTS/PTS thresholds) on marine animals exposed to active sonars and other active acoustic sources utilized during Navy training and testing activities. (Report link)

Follow-up to second external review: Concurrent with the third public comment period, NOAA requested that peer reviewers of the Navy's methodology review the updated sections of the Draft Guidance and indicate whether the revisions would significantly alter any of the comments made during their original review. (Follow-up peer review charge link)

The third external peer review evaluated proposed methodology for defining threshold usage for sources characterized as impulsive or non-impulsive. This methodology was modified using comments from the initial public comment period. (Report link)

More information about these additional peer reviews

First Public Comment Period

The comment period on the initial draft guidance opened in December 2013 (78 FR 78822) and closed on March 13, 2014 (79 FR 4672). Comments received are available on

During this time NOAA Fisheries held a public meeting to inform interested parties and solicit comments on the proposed acoustic guidance. The meeting was held on January 14, 2014, in the NOAA Science Center in Silver Spring, MD. A transcript from the meeting is available as well as the Public Meeting One-Pager [pdf] and Presentation [pdf].

Second Public Comment Period

The second public comment period opened on July 31, 2015 and closed September 14, 2015 (80 FR 45642). Comments received are available on

Third Public Comment Period

The third public comment period opened on March 16, 2016 and closed March 30, 2016 (81 FR 14095). Comments received are available on


The following additional information and resources are provided as part of the Technical Guidance's finalization:

Frequently Asked Questions Regarding NOAA Fisheries' Technical Acoustic Guidance are also available (updated May 2017).


For more information, please contact:

Amy R. Scholik-Schlomer
NMFS Protected Resources Acoustic Coordinator
1315 East West Highway
Silver Spring, MD 20910

Updated: May 30, 2017