Heal, Katherine R., and Kaustubha Raghukumar. “Underwater soundscape and vector acoustic observations during a seismic airgun survey near coastal Oregon.” The Journal of the Acoustical Society of America 157.5 (2025): 3848-3859.
Abstract
In the summer of 2021, a seismic survey occurred near Southern Oregon to map the Cascadia Subduction Zone using an array of airguns. To evaluate the effect of the survey on the soundscape within a marine protected area, acoustic measurements were conducted using a vector sensor array deployed in 36 m deep water. Resulting data were analyzed using acoustic metrics, some of which are commonly used in soundscape studies, while others are gaining popularity in ecological acoustics. While cumulative sound exposure levels were dominated by wind noise, other metrics such as peak sound pressure, kurtosis, Acoustic Complexity Index, and crest factor, showed clear signals associated with the seismic survey. Further, when the seismic survey vessel was closest to the measurement location, a good correlation was observed between sound pressure (peak and root mean squared) and sound exposure levels computed using sound pressure versus those computed using particle velocity. At lower signal-to-noise ratios, or in the absence of seismic pulses, velocity-based acoustic metrics showed considerable contamination by flow and other noise. Our analysis suggests that pressure measurements alone may be sufficient (and even preferable) for evaluating organismal particle velocity dosage, whenever the signals of interest have sufficient signal-to-noise ratio.
Keywords: Acoustic metric, Acoustical properties, Aeroacoustics, Acoustic noise, Spectrograms, Acoustic ecology, Electrical properties and parameters, Seismology, Linear filters, Signal-to-noise ratio