Deep-water measurements of container ship radiated noise signatures and directionality

TitleDeep-water measurements of container ship radiated noise signatures and directionality
Publication TypeJournal Article
Year of Publication2017
AuthorsGassmann M., Wiggins SM, Hildebrand JA
JournalJournal of the Acoustical Society of America
Volume142
Pagination1563-1574
Date Published2017/09
Type of ArticleArticle
ISBN Number0001-4966
Accession NumberWOS:000412100700047
Keywordsmodel; ocean; shallow-water; spectra; whales
Abstract

Underwater radiated noise from merchant ships was measured opportunistically from multiple spatial aspects to estimate signature source levels and directionality. Transiting ships were tracked via the Automatic Identification System in a shipping lane while acoustic pressure was measured at the ships' keel and beam aspects. Port and starboard beam aspects were 15 degrees, 30 degrees, and 45 degrees in compliance with ship noise measurements standards [ANSI/ASA S12.64 (2009) and ISO 17208-1 (2016)]. Additional recordings were made at a 10 degrees starboard aspect. Source levels were derived with a spherical propagation (surface-affected) or a modified Lloyd's mirror model to account for interference from surface reflections (surface-corrected). Ship source depths were estimated from spectral differences between measurements at different beam aspects. Results were exemplified with a 4870 and a 10 036 twenty-foot equivalent unit container ship at 40%-56% and 87% of service speeds, respectively. For the larger ship, opportunistic ANSI/ISO broadband levels were 195 (surface-affected) and 209 (surface-corrected) dB re 1 mu Pa-2 1 m. Directionality at a propeller blade rate of 8 Hz exhibited asymmetries in stern-bow (< 6 dB) and port-starboard (< 9 dB) direction. Previously reported broadband levels at 10 degrees aspect from McKenna, Ross, Wiggins, and Hildebrand [(2012b). J. Acoust. Soc. Am. 131, 92-103] may be similar to 12 dB lower than respective surface-affected ANSI/ISO standard derived levels. (C) 2017 Acoustical Society of America.

DOI10.1121/1.5001063
Student Publication: 
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