Humpback Whale Acoustics Research with the novel Hydroambiphone

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Blue Pearl
Southeast Alaska, Alaska
May 25 - June 8, 2024

Program Overview

Recording the undersea three-dimensional bioacoustic sound field in real-time promises major benefits to marine behavior studies. We describe a novel hydrophone array — the hydroambiphone (HAP) — that adapts ambisonic spatial-audio theory to sound propagation in ocean waters to realize many of these benefits through spatial localization and acoustic immersion. Deploying it to monitor the humpback whales (Megaptera novaeangliae) of southeast Alaska demonstrates that HAP recording provides a qualitatively improved experience of their undersea behaviors; revealing, for example, new aspects of social coordination during bubble-net feeding. On the practical side, spatialized hydrophone recording greatly reduces post-field analytical and computational challenges—such as the “cocktail party problem” of distinguishing single sources in a complicated and crowded auditory environment—that are common to field recordings. On the scientific side, comparing the HAP’s capabilities to single-hydrophone and non-spatialized recordings yields new insights into the spatial information that allows animals to thrive in complex acoustic environments. Spatialized bioacoustics markedly improves access to the humpbacks’ undersea acoustic environment and expands our appreciation of their rich vocal lives. The complete description of the ongoing research can be found in the attached document: J.P. Crutchfield, D. D. Dunn, and A. M. Jurgens, “Whales in Space: Experiencing Aquatic Animals in Their Natural Place with the Hydroambiphone” bioRxiv.org (2023) 2023.12.27.573441.
Attached.

Application

This trip was focused on developing new acoustic monitoring tools and techniques for marine biology. If successful, we will be able to locate and track marine mammals via their underwater vocalizations.

This research can have far-reaching applications when decoding other non-human intelligence and communication. the more immediate benefit here is that we can better protect and conserve, not only whales but any other species with which we can communicate.

Expedition Summary

From May 25th to June 8th, 2024, The International SeaKeepers Society facilitated a research expedition aboard DISCOVERY Yacht Blue Pearl with a science team led by Dr. James Crutchfield of the University of California, Davis. During the fourteen days aboard Blue Pearl, the studies we initially conducted in 2023 were extended to include simultaneous recordings using two hydroambiphones deployed from the support vessel, multiplying the spatial effectiveness of the recording. Analysis of the recorded data will continue throughout the year.

Recordings were made daily, often for several hours continuously, to gain perspective on behavior throughout the day. In order to make the recordings without human sound interference, all mechanical systems were shut down and Blue Pearl drifted silently, for the duration of each recording.

Location

Southeast Alaska, largely in Chatham Strait

Duration of Project

Ongoing since 2023 (each expedition is about 14 days in duration)

Research Team

  • James P. Crutchfield, PhD
  • David D. Dunn, PhD
  • Alexandra M. Jurgens, PhD

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