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NRS Hybrid Millidecade Spectra

Published by NOAA National Centers for Environmental Information | National Oceanic and Atmospheric Administration, Department of Commerce | Metadata Last Checked: December 19, 2025 | Last Modified: 2023-07-01T00:00:00.000+00:00
To understand natural and anthropogenic sound in the ocean, and to compare underwater soundscapes globally, standard methods of analysis must be applied to passive acoustic monitoring (PAM) data. Methods that balance constrained volume and adequate resolution of acoustic spectra have recently been published (Martin et al., 2021a,b). A community effort supported by NOAA, BOEM, U.S. Navy, and ONR was initiated to apply these methods to PAM datasets from around the world. This record represents the hybrid millidecade (HMD) spectra of sound levels derived from calibrated passive acoustic data. Daily HMD at 1 minute resolution were created using standalone MANTA software.

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