Detection and Characterization of Unidentified Underwater Biological Sounds, Their Spatiotemporal Patterns and Possible Sources.

This Research Topic focuses on documenting and describing a significant component of marine and freshwater soundscapes, that of unidentified underwater biological sounds. These sounds maybe be actively produced, such as the calls of marine mammals or fish, or passively produced, such as the grinding off teeth while eating or crawling across a reef. Whether detected as individual sounds or mass phenomena (e.g., fish choruses), these signals provide significant knowledge about the local acoustic community, as a proxy for biodiversity and ecosystem health, even though the source is yet to be identified. Increasing our knowledge of unidentified sounds is of significant benefit to passive acoustic monitoring and the assessment of underwater soundscapes and documenting them now provides a baseline for their presence and supporting information later source identification.

Unidentified underwater sounds are not commonly a project priority and so are rarely reported, often remaining an elusive, yet valuable source of acoustic information. This knowledge gap can be alleviated through open access sharing and reporting of their characteristics and spatiotemporal distribution, together with potential methods to identify the sources and behaviors are associated with the sound. The aim of this Research Topic is to provide a focus area where information about such signals can be shared for future comparison. This topic is supported by the International Quiet Ocean Experiment, via the Global Library of Underwater Biological Sounds.

This Research Topic calls for papers that:

• Develop detection algorithms with a focus on unidentified underwater biological sounds;
• Quantitatively characterize spatiotemporal patterns in individual or mass phenomena unidentified sounds;
• Compare characteristics of unidentified sounds to similar known sounds, to assist source identification;
• Examples of where recordings of sounds from known sources exhibit atypical temporal or spectral characteristics, resulting from behavioral change or propagation conditions, and how this may affect detection performance; and
• Techniques to validate sound sources.

This topic is supported by the International Quiet Ocean Experiment, via the Global Library of Underwater Biological Sounds. We acknowledge the partial funding of the manuscripts published in this Research Topic by Université de Perpignan provided through a Richard Lounsbury Foundation grant. We hereby state publicly that neither Université de Perpignan or the Richard Lounsbery Foundation has had any editorial input in articles included in this Research Topic, thus ensuring that all aspects of this Research Topic are evaluated objectively, unbiased by any specific policy or opinion of Université de Perpignan or the Richard Lounsbery Foundation.