Point measurements of ambient biological noise before, during, and after multiple underwater detonation events over coral substrate off the southern coast of Oahu, Hawai

• Published in: The Journal of the Acoustical Society of America 2016-10, Vol.140 (4), p.3171-3171
• Main Authors: Farrell, Dara M., Shannon, Lee H., Dahl, Peter H., Dall'Osto, David R.
• Format: Article
• Language: English
• ISSN: 0001-4966; 1520-8524
• DOI: 10.1121/1.4969962

Measurements were taken of background noise at the U.S. Navy's Pu‘uloa Underwater Detonation Range off the south coast of O‘ahu during a U.S. Navy underwater explosive training exercise in shallow water (10-18 m) where distance from the detonation site, charge size, and explosive composition were controlled. The autonomous recording unit was deployed approximately 1500 m from the detonation location. The combined data from the paired low (-220 dB re 1 V /μPa) and high (-170 dB re 1 V /μPa) sensitivity hydrophones gives an approximately 100 dB dynamic range view of each event. Each trial consisted of three replicate events per charge weight (2.2, 4.5, and 8.6 kg) for a total of nine explosive events over the coral substrate. An analysis of the background noise environment immediately before and after each replicate is presented using metrics such as spectral probability density. Results are considered in the context of typical coral reef noise including discussion of snapping shrimp noise (one of the dominant features of the soundscape) before and after each event. [Work supported by U.S. Pacific Fleet.]