Analysis and Ranking of the Acoustic Disturbance Potential of ...

Report No. 6945
BBN Systems and Technologies Corporation
in Section 3 as graphs and tables of 1/3 octave source level. When available,
information on the temporal characteristics of the sources is also included.
Knowledge of acoustic transmission loss characteristics is required to
estimate the effective acoustic ranges of sound sources from given source
level information. For the purpose of this study both airborne and underwater
transmission loss characteristics are required. However, empirical information
on underwater acoustic transmission loss in the Alaskan marine environment
is sparse. As a result, it was necessary to use sound propagation models
to obtain estimated transmission loss characteristics for several areas
studied. The procedures employed and the results of the transmission loss
analysis are presented in Section 4.
Information on species distribution was combined with information on
source distribution, source level, and transmission loss to determine the most
significant sources in terms of their acoustic ranges and the numbers of
mammals potentially affected. This was done by developing a Standardized
Noise Contribution Model, which is based on the acoustic energy density
contributed to the environment by a specific type of source in a defined
reference area. The source rating is combined with a Standardized Exposure
Rating Model for a specific species. The latter model takes into account the
degree of matching between the source bandwidth and the frequency band to
which that species is most sensitive, the species hearing sensitivity, and the
number of animals present in the reference area. The output of this procedure
provides an indication of which source - species1 combinations may have the
highest potential for acoustic interaction in a given area. The development
of this procedure and the results are described in Section 5. That section
also includes estimated zones of influence for the major sound sources, as
determined by the modeling procedure, in the four OCS planning areas selected
for principal study concentration - Chukchi Sea, Norton Basin, North Aleutian
Basin, and Shumagin. A Glossary of specialized terminology and an Index are
provided following the conclusions and recommendations in Section 6.
The References Cited section contains all of the references cited in the
preceding sections. Detailed information supplementing the discussion in
Sections 1 - 5 is presented in the Appendices.
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