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Humpback whale breathing-related sounds were recorded on elements of a coherent hydrophone array subaperture deployed vertically at the Great South Channel on the US Northeastern continental shelf in Fall 2021, where half of the hydrophones were in-air and the rest submerged underwater. In-air hydrophones recorded breathing sounds with approximately 2.5 s duration, but smaller bandwidths compared to underwater hydrophones where signal energies extended beyond 50 kHz, and a mean underwater source level of 161 ± 4 dB re 1 μPa at 1 m, based on measurements at 22.9 m. The underwater recorded humpback whale breathing sound spectra displayed a broadband dip centered at 15.7 kHz, with approximately 400 Hz half-power bandwidth, likely caused by attenuation from propagation through pulsating air bubbles. The air bubble radius for natural frequency of oscillations at 15.7 kHz is estimated to be 0.205–0.21 mm. These bubbles are capable of removing energy from the forward propagated humpback breathing sounds via resonance absorption most pronounced at and near bubble natural oscillation frequency. Humpback whale distances from the vertically deployed hydrophones are estimated and tracked by matching the curved nonlinear travel-time wavefront of its breathing sounds, since the whale was in the near-field of the subarray.
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Underwater Acoustics for All: Expanding Capacity with Education and Low-Cost Sensors
Sound is a persistent yet dynamic component of the marine environment, reflecting both physical and biological properties. Whereas light can only travel tens of meters in the ocean, sound is able to travel tens to thousands of kilometers under certain conditions, revealing information at specific times and places. In addition, underwater sound provides opportunities for sustainable development and blue economy growth that aren’t readily available with other technologies. For example, the melting rate of Arctic ice and the health of coral reefs can be estimated from acoustic measurements (Becker et al., 2023). However, underwater acoustics is a complex topic, requiring specialized education and equipment. To expand the capacity of underwater acousticians requires dedicated educational opportunities and low-cost equipment and analysis resources.
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- Award ID(s):
- 2318309
- PAR ID:
- 10599694
- Publisher / Repository:
- The Oceanography Society
- Date Published:
- Journal Name:
- Oceanography
- ISSN:
- 1042-8275
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript
- Journal Article:
- https://doi.org/10.5670/oceanog.2025.107
