01889nas a2200157   4500008004100000022001400041245008700055210006900142260001600211300001400227490000800241520138700249100002201636700002201658856005101680       2018                        eng d  a0001-496600aAcoustic characterization of exploration drilling in the Chukchi and Beaufort seas0 aAcoustic characterization of exploration drilling in the Chukchi  cJan-07-2018  a115 - 1230 v1443 a<p>This paper characterizes underwater sound levels produced by three drilling units during offshore exploration drilling at three sites in the Beaufort and Chukchi seas. Received levels and spectra are reported as functions of distance during drilling and excavation of mudline cellars (MLCs). Sound levels emitted during MLC excavation exceeded those during drilling at all three sites, although this operation was much shorter in duration. Drilling sounds exhibited tones below 2&thinsp;kHz, with harmonics present to 10&thinsp;kHz, while MLC excavation sounds were broadband in character. Drilling sounds varied substantially between the three operations, whereas MLC excavation sounds were more consistent in amplitude and spectral distribution. Estimates of broadband and 1/3-octave band source levels were computed from measurements at 1&thinsp;km range. The broadband drilling source levels were 168.6&thinsp;dB re 1&thinsp;&mu;Pa m for the Kulluk drilling unit, 174.9&thinsp;dB re 1&thinsp;&mu;Pa m for the drillship Noble Discoverer, and 170.1&thinsp;dB re 1&thinsp;&mu;Pa m for the semi-submersible Polar Pioneer. The received levels measured at 1&thinsp;km during MLC excavation yielded source level estimates that were more consistent among sources: 191.8, 193.0, and 193.3&thinsp;dB re 1&thinsp;&mu;Pa for the Discoverer, Kulluk, and Polar Pioneer, respectively.</p>
1 aHannay, David, E.1 aBröker, Koen, C.  uhttp://asa.scitation.org/doi/10.1121/1.5044417