Anthropogenic Noise in Cook Inlet Beluga Habitat: Sources Acoustic Characteristics and Frequency of Occurrence
Anthropogenic acoustic events in Cook Inlet, Alaska
A subsample (8756 hours) of the acoustic recordings collected by the Cook Inlet Beluga Acoustics research program in Cook Inlet, Alaska, from July 2008 to May 2013, were analyzed to describe anthropogenic sources of underwater noise, acoustic characteristics, and frequency of occurrence and evaluate the potential for acoustic impact to Cook Inlet belugas. A total of 13 sources of noise were identified: Commercial ship, dredging, helicopter, jet aircraft (commercial or non-fighter), jet aircraft (military fighter), outboard engine (small skiffs, rafts), pile driving, propeller aircraft, sub-bottom profiler, unclassified machinery (continuous mechanical sound; e.g., engine), unidentified 'clank' or 'bang' (impulsive mechanical sound; e.g., barge dumping), unidentified (unclassifiable anthropogenic sound), unknown up- or down-sweep (modulated tone of mechanical origin; e.g., hydraulics). Several noise metrics were calculated (SLP in dB rms, SEL, dB 0-peak, power spectral density, 1/3 octave bands, and duration) and results were compared across noise sources, months, and locations. A total of 6263 anthropogenic acoustic events were detected and classified, which had a total duration of 1025 hours and represented 11.7% of the sound recordings analyzed.