title: Airgun inter-pulse noise field during a seismic survey in an Arctic ultra shallow marine environment.
abstract: Offshore oil and gas exploration using seismic airguns generates intense underwater pulses that could cause marine mammal hearing impairment and/or behavioral disturbances. However, few studies have investigated the resulting multipath propagation and reverberation from airgun pulses. This research uses continuous acoustic recordings collected in the Arctic during a low-level open-water shallow marine seismic survey, to measure noise levels between airgun pulses. Two methods were used to quantify noise levels during these inter-pulse intervals. The first, based on calculating the root-mean-square sound pressure level in various sub-intervals, is referred to as the increment computation method, and the second, which employs the Hilbert transform to calculate instantaneous acoustic amplitudes, is referred to as the Hilbert transform method. Analyses using both methods yield similar results, showing that the inter-pulse sound field exceeds ambient noise levels by as much as 9 dB during relatively quiet conditions. Inter-pulse noise levels are also related to the source distance, probably due to the higher reverberant conditions of the very shallow water environment. These methods can be used to quantify acoustic environment impacts from anthropogenic transient noises (e.g., seismic pulses, impact pile driving, and sonar pings) and to address potential acoustic masking affecting marine mammals.
authors.affiliation: Office of Protected Resources, National Marine Fisheries Service, 1315 East-West Highway, SSMC-3 Suite 13826, Silver Spring, Maryland 20910, USA.
authors.forename: Shane
authors.initials: S
authors.lastname: Guan
authors.affiliation: Department of Mechanical Engineering, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Vignola
authors.affiliation: Department of Mechanical Engineering, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA.
authors.forename: John
authors.initials: J
authors.lastname: Judge
authors.affiliation: Department of Mechanical Engineering, The Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064, USA.
authors.forename: Diego
authors.initials: D
authors.lastname: Turo
mesh_terms: D000162:Acoustics / Q000295:instrumentation; D001110:Arctic Regions; D004864:Equipment and Supplies; D005844:Geology / Q000295:instrumentation / Q000379:methods*; D008962:Models, Theoretical; D009038:Motion; D009792:Oceans and Seas; D061329:Oil and Gas Fields; D000066388:Oil and Gas Industry / Q000295:instrumentation / Q000379:methods*; D011312:Pressure; D012815:Signal Processing, Computer-Assisted; D013016:Sound; D013018:Sound Spectrography; D013997:Time Factors; D014732:Vibration; D014867:Water
chemical_list: D014867:Water