Page 51 - January 2006

different PAM activities can be objectively compared by a neutral observer. For example, PAM measurements made from a large ship and a small sailboat in the same area might reach different conclusions about the presence or absence of a particular species in the area. In this situation it would be important that information about the background noise levels recorded on both systems be declared in the report, as well as the sampling rates, dynamic range, and frequency response of the two systems.
(3) To provide a set of minimum metrics for character- izing and reporting marine animal vocalization fea- tures, particularly those features that concern source level. It is hoped that greater consistency in reporting sound characteristics is achieved.
(4) To recommend a set of additional procedures that would allow data collected by non-specialists on non- research platforms to be used for research into marine animal source levels, directionality, and ocean sound propagation loss, which in turn may eventually have relevance to studies of sound impacts on marine mammals.
(5) To simplify drafting regulations, cruise plans, and reports by standardizing some basic procedures for col- lecting acoustic data for PAM purposes. Rather than reiterating these procedures, these documents may simply refer to the ANSI standard for the essential requirements.
(6) To ensure that reports that use PAM data for nonre- search purposes directly state the limits and uncertain- ties associated with PAM.
(7) To encourage the market to develop an expendable, calibrated sound source to allow PAM detection range to be empirically measured.
This standard would not cover active underwater detec- tion of marine animals or nonacoustic means of detecting and ranging animals, nor address criteria for noise impacts on marine animal behavior and long-term viability of popu- lations.
There have been concerns expressed that many PAM systems are still under development, and new hardware and software systems are tested all the time. Wouldn’t an ANSI standard quickly become irrelevant, or worse, stifle innova- tion and research into the topic? To calm these concerns the draft outline of the standard stresses good procedure over specific equipment needs.
Another fundamental strategy behind the standard is to
“The use of passive acoustic monitoring methods...has spread beyond the research community and is now being used by a variety of government agencies, non- government organizations, and consultants.”
specify minimum amounts of informa- tion that need to be published in a PAM report to allow correct comparison between different activities. Thus much of the standard will consist of reporting requirements.
There are several issues that have caused some disagreement, such as whether a set of procedures for report- ing source levels for different types of biological sounds (particularly impul- sive sounds) can be standardized at this point. Therefore, among others, the opinions of Acoustical Society of America members from all technical committees are being invited, particu- larly members from Animal
Bioacoustics,
Oceanography, and Signal Processing in Acoustics.
Underwater Acoustics, Acoustical
The last working group meeting occurred at the 16th Biennial Conference on the Biology of Marine Mammals, at the Manchester Grand Hyatt San Diego in San Diego, CA, on December 15, 2005. Twenty-five people attended the meet- ing, and much discussion took place about the need for and scope of a standard for passive acoustic monitoring. While strong opinions were expressed about the value or timing of such a standard, the group reached a consensus that a mini- mum standard should be defined that would specify mini- mum "metadata" that should be recorded during PAM activ- ities, as a first step toward a possible standard for recording and reporting of acoustic data at sea. Clearly, the effort is still in its early stages, and individuals who are interested in help- ing to formulate the standard are encouraged to attend the next working group meeting at the next ASA meeting in Providence, RI on Wednesday, June 7. Individuals who are interested in helping to formulate the text for the standard are encouraged to attend this meeting, and sign up on the ASA- PAM-STANDARD mailing list using the URL: siomail.ucsd.edu/mailman/listinfo/asa-pam-standard. AT
References and Further Reading
1. W.J. Richardson, Jr., C.R. Greene, C.I. Malme, and D.H. Thomson, Marine Mammals and Noise. (Academic Press, Inc., San Diego, 1995).
2. William A. Watkins and William E. Schevill, “Sperm Whale Codas,” J. Acoust. Soc. Am. 62(6), 1485–1490 (1977).
3. Hal Whitehead, Sperm Whales: Social Evolution in the Ocean. (University of Chicago Press, Chicago, IL, 2003).
4. L.E. Rendell and H. Whitehead, “Spatial and temporal variation in sperm whale coda vocalizations: Stable usage and local dialects.” Animal Behaviour 70, 191–198, (2005).
5. V. Drouot, J.C. Goold, and A. Gannier, “Regional diversity in the social vocalizations of sperm whale in the Mediterranean Sea.” Revue D Ecologie-La Terre Et La Vie 59(4), 545–558. ISSN: 0249–7395
Standards News 49