Performance of an Acoustic Sensing Array in an Energetic Tidal Channel

In support of environmental monitoring technologies to evaluate the acoustic impact of marine energy operations, a cost-effective compact array of acoustic sensors has been developed that characterizes, classifies, and provides accurate location information for anthropogenic and natural sounds in real time. The NoiseSpotter consists of a three-dimensional bottom-mounted array of three acoustic vector sensors cabled to a surface buoy for real-time telemetry. Each sensor measures acoustic pressure and three-dimensional particle velocity associated with the propagation of an acoustic wave.

The NoiseSpotter was deployed in an energetic tidal channel with a tidal oscillation that can approach 3 m. Performance characteristics in the presence of the resulting flow noise is quantified, and a flow noise suppression system is quantitatively shown to significantly improve performance, with flow noise suppression close to 15 dB. Performance is significantly improved when the sensors are housed in a flow noise removal shield, which provides acoustic transparency while reducing non-acoustic signal contamination. Long term durability of this flow-noise suppression shield is demonstrated using biofouling experiments. The real-time telemetry of data digests is demonstrated to allow rapid decision-making in response to measured sound intensity levels.

This paper was co-authored by Kaustubha Raghukumar; Grace Chang; Frank Wayne Spada; Craig Alexander Jones