Vibrational Noise in Aquatic and Terrestrial Substrates: Current Status and Future Directions for the Study of Overlooked Substrate-Borne Stimuli

Humans are contributing not only anthropogenic acoustic noise to the environment, but they are also contributing vibrational noise to landscapes. This occurs via substrate-borne waves produced either by direct contact such as from construction and transport, or indirectly via high-intensity sound sources. Substrata and sediments of varied types exist across land and sea, within which substrate-borne vibrations can travel (bounded by air, water, or both). Animals associated with substrates exist in both aquatic and terrestrial domains, with hundreds of thousands of species specifically utilizing substrate-borne vibration for communication and sensing. Yet despite the prevalence of acoustic studies, there are very few studies focused upon vibrational noise, particularly in aquatic environments. A brief overview of vibrational noise is given here, using the current status of the field, with a goal of helping to define future directions for this overlooked area of noise research. Common themes in the literature include incomplete coverage of vibrational noise source types, inconsistencies in measurement units, partial source characterization, and missing information regarding ambient landscapes. A trio of guiding principles is discussed here, particularly focused around aquatic systems. Importantly, vibrational noise is highlighted as an area which requires more research attention across all environments.