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Updated: Sep 13, 2026

A Stable Phantom Material for Optical and Acoustic Imaging
Published on: June 16, 2023
Azipod-equipped vessels in the Antarctic Peninsula radiate underwater continuous mid-frequency narrowband and tonal
Julien Bonnel1, Alex Mira2,3, Alessandro Bocconcelli4
1Marine Physical Laboratory, Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA.
Abstract:
It is commonly accepted that ocean noise from marine traffic is mostly confined to low frequencies. This article empirically demonstrates that large (length >120 m) vessels equipped with electrically driven "Azipod" propulsion systems generate loud mid-frequency (3-15 kHz) tonal and mid-frequency narrowband and tonal sounds (MF-NTS). The study focuses on six Azipod-equipped tourist vessels operating in the Antarctic Peninsula; it relies on opportunistic passive acoustic measurements collected there during the 2024-2025 Austral summer. The six vessels considered here all radiate MF-NTS, which are interpreted as the acoustic signature of the Azipod (data below 2 kHz are not considered in this study). This signature dominates the ambient sound for several kilometers around the vessel, and can be acoustically detected at ranges exceeding 5 km.
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