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NOAA's Marine Mammal Acoustic Technical Guidance

Status of NOAA's Technical Guidance for Assessing the Effects of Anthropogenic Sound on Marine Mammals

The National Oceanic and Atmospheric Administration (NOAA) is holding a third public comment period on a stand-alone document containing proposed changes to our draft acoustic guidance for assessing the effects of anthropogenic sound on marine mammal species [pdf] under our jurisdiction.

While NOAA was working to address public comments from the second public comment period and finalize the Guidance, NOAA and the Navy further evaluated certain aspects of the U.S. Navy's methodology (Appendix A of Draft Guidance). As a result, several recommendations/modifications were suggested. After consideration of these recommendations. NOAA has revised the Draft Guidance to reflect these suggested changes and is proposing to solicit public comment on these changes via a focused public comment period.

The third public comment period will last 14-days and begin on March 16. Comment now  (Note: Please be sure to comment on the document containing the proposed changes to the Guidance, which is a 24-page stand-alone document separate from the July 2015 Draft Guidance. All other aspects of the Guidance remain unchanged).

Before the Guidance is finalized (anticipated May 2016), NOAA will address all substantive comments received from the initial and second public comment periods, as well as those from this focused third public comment period. There is no need to reiterate or resubmit comments made during the first and second public comment periods on other sections of the Draft Guidance. NOAA encourages the public to focus comment on the proposed changes to the document.

Purpose of the Acoustic Guidance

The Technical Guidance provides acoustic threshold levels for onset of permanent threshold shift (PTS) and temporary threshold shifts (TTS) for all sound sources. It is intended to be used by NOAA analysts/managers and other relevant user groups/stakeholders, including other federal agencies to better predict a marine mammal’s response to sound exposure. The manner of response has the potential to trigger certain requirements under one or more of NOAA’s statutes (MMPA, ESA, and National Marine Sanctuaries Act).

To develop these acoustic threshold levels, NOAA has compiled, interpreted, and synthesized best available information currently available on the effects of anthropogenic sound on marine mammals, as well as developed a method for updating these levels through a systematic, transparent process. The document outlines NOAA's updated acoustic threshold levels 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 year on developing guidance regarding the effects of anthropogenic sound on marine mammal behavior.

Process to Develop Acoustic Technical Guidance

The process to finalize the guidelines includes the following steps:

  1. NOAA internal review
  2. External peer review
  3. Public comment
  4. Finalize and release guidance

NOAA's draft acoustic Guidance [pdf] has undergone an internal review, 3 external peer reviews, 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 threshold levels. (Report link)

The second external peer review evaluates 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)

The third external peer review evaluates NOAA's 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 ends on March 30, 2016. Comment now on these proposed changes.

Once the comments from all three public comment periods are addressed, NOAA will finalize and release the acoustic guidance fro onset PTS and TTS.

Frequently Asked Questions Regarding NOAA's Acoustic Guidance are also available (updated February 2016).

For more information, please contact:

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

Updated: March 14, 2016