Whales in Space:
Experiencing Aquatic Animals in Their Natural Place with the Hydroambiphone

ABSTRACT: 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 nonspatialized 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.

AI ABSTRACT:

Hydroambiphone: Spatializing Whale Vocalizations and Undersea Sound

The source documents the creation and field testing of a novel marine instrument called the hydroambiphone (HAP), which is designed to improve bioacoustic research. This device successfully adapts Ambisonics spatial-audio theory to the ocean environment, utilizing a specialized four-hydrophone array to capture the undersea three-dimensional sound field in real-time. A major benefit of this spatialized recording technique is that it provides accurate source localization, alleviating the complex post-analysis challenges common in traditional recordings. During its deployment in southeast Alaska to monitor humpback whales, the HAP revealed a wealth of acoustic activity, including the surprising discovery of two individuals harmonizing their calls during coordinated bubble-net feeding. The HAP's high sensitivity and ability to create an immersive acoustic experience demonstrate its utility as a new tool for expanding scientific access to the rich underwater world of cetaceans.

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COMPACT DISC:

• Whales in Space (HAP recordings, 55 minutes)
• Disc liner notes