Greetings,
We would like to announce that a new paper on underwater source levels
of 12 classes of ships has been published in the open-access,
peer-reviewed journal PeerJ.
Veirs S, Veirs V, Wood JD. (2016) Ship noise extends to frequencies used
for echolocation by endangered killer whales. PeerJ 4:e1657
https://doi.org/10.7717/peerj.1657
Main findings from ~2,800 measurements of ~1,600 unique ships in 12 classes:
-- In the Salish Sea ships dominate the soundscape (~20 ships/day,
year-round; mean+/-s.d. broadband source level of 173 +/- 7 dB re 1 uPa
@ 1m)
-- Median noise spectrum levels received in killer whale habitat (2 km
from shipping lane) were raised 5-30 dB (re 1 uPa^2@/Hz) above
background by ships at all reported frequencies (11.5 Hz - 40,000 Hz).
-- Source spectra of different ship classes show similar levels above
20,000 Hz, but bifurcation into lower and higher power groups at lower
frequencies (~20 dB re 1 uPa^2/Hz @ 1 m difference at the 50 Hz power peak).
-- Container ships have highest median spectrum levels; military ships
have some of the lowest levels, especially below 1,000 Hz.
-- Within each class, source spectrum levels vary 15-30 dB re 1 uPa^2/Hz
@ 1 m between the 5% and 95% quantiles.
Supplemental information (R scripts, data, example mp3 files) can be
accessed here:
http://www.beamreach.org/data/staff-research/ship-noise/
We hope this characterization of ship noise will help inform models of
potential impacts on marine life, development of policies regarding
ocean noise, and strategies for mitigating noise pollution from ships.
Best regards,
Scott, Val, and Jason
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