but
IMO shipping noise reduction effort appears adrift at sea
The San Juan Straits and Gulf of Alaska are major shipping areas. For passive sonar, shipping noise is one of the primary masks for submarine radiated noise, making both nuclear and diesel boats hard to detect. Urick, the handbook of sonar had a formula predicting ship radiated noise versus displacement and speed. The Navy has current more sophisticated models. The advent of huge displacement ships such as VLCC surely has exacerbated the noise problem. Marine mammals who use the same frequencies for communication would have difficulties.
Noise, Sonar, and Marine Mammals
Ship-Induced Noise Predictions in the Atlantic and the Pacific: A ...PDF Url : ADA473782
www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA473782
May 30, 2006 - This report describes differences in the ship-induced,
bearing-elevation, noise directionality obtained from different noise
models and interprets those differences in terms of the propagation and
the environmental components of those models. The two noise models,
RANDI and APL, both compute the noise as the incoherent sum of the
individual ship contributions; they differ in both their propagation
models (ANM and FEPE) and in their environmental models. The
directionalities are computed for both the Sargasso Sea and the Gulf of
Alaska. The Sargasso Sea results differ significantly with the APL
directionality, showing lower levels and a much deeper noise notch. In
the Gulf of Alaska, the directionalities are much more similar, with
both exhibiting deeper noise notches than in the Sargasso Sea. The
disparity in the Sargasso Sea noise notch results primarily because, for
the ANM model, the set of modes excited by sources near the continental
shelf is disjoint from the modes observed by the array. For the Gulf of
Alaska, this "mode-set-disjunction" does not occur, and hence, the ANM
more realistically estimates the downslope propagating contributions..Historical recordings of ocean noise
Shipping noise and marine mammals: A forum for … - Southall
Final Report of the 2004 NOAA symposium “Shipping Noise and Marine Mammals”
A push for quieter ships - Bank
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