Estimating sound pressure levels from distributed acoustic sensing data using 20 Hz fin whale calls
Illustration of fin whale calls recorded on a seafloor fiber optic cable using DAS.
Abstract
Distributed acoustic sensing (DAS) is a promising technology for underwater acoustics, but its instrumental response is still being investigated to enable quantitative measurements. We use fin whale 20 Hz calls to estimate the conversion between DAS-recorded strain and acoustic pressure. Our method is tested across three deployments on varied seafloor telecommunication cables and ocean basins. Results show that after accounting for well-established DAS response factors, a unique value for water compressibility provides a good estimate for the conversion. This work represents a significant step forward in characterizing DAS for marine monitoring and highlights potential limitations related to instrument noise floor.
This research presents a novel method to calibrate Distributed Acoustic Sensing (DAS) data for quantitative underwater acoustic measurements. By analyzing the well-known 20 Hz calls of fin whales recorded on different seafloor telecom cables, we developed a robust conversion factor between the strain measured by the fiber and the actual acoustic pressure in the water.
This work is a significant step towards using existing global fiber optic networks for passive acoustic monitoring of marine life and other underwater sound sources.