Underwater particle motion (acceleration, velocity and displacement) from recreational swimmers, divers, surfers and kayakers
When humans take to the water, they generate sound. This is helpful for the detection, classification, localisation and tracking of certain activities for purposes of border security, health and safety of offshore industrial development, environmental management, etc. The most commonly measured acoustic quantity is pressure. Vector quantities related to particle motion, such as particle velocity and acceleration, can equally identify the activity and they carry directional information. Acoustic pressure and particle motion were measured from 10 water sports activities within an Olympic-sized pool: swimming backstroke, breaststroke, butterfly and freestyle; snorkelling with fins; kicking a boogie board with fins; paddling with alternating or simultaneous arms while lying on a surfboard; scuba-diving; kayaking and jumping into the pool. Activities that occurred at the surface and that involved repeatedly piercing the surface were the strongest sound generators. Surface activities that produced fewer bubbles and scuba-diving at depth generated less broadband power. The vector fields around water sports activities can be expected somewhat different in the open ocean from within a pool, and more research is needed to understand how marine fauna might perceive these vector quantities.
KeywordsParticle motion Particle velocity Underwater sound Swimmers Kayakers Scuba-diving
The authors thank Leila Fouda, Sven Gastauer, Sylvia Osterrieder, Nicholas Riddoch and Rebecca Wellard, all of the Centre for Marine Science and Technology at the time, for swimming in a cold public pool during the off-season. David Minchin and Malcolm Perry kindly assisted with equipment preparation, calibration and data collection. The authors are also grateful to Scotch College and the University of Western Australia for the use of their pools during tests.
Funding This study was funded by the Western Australian Government, Office of Science, under the Applied Research Program—Round 2. The Western Australian Government does not endorse any information, product, process or outcome, arising from or in relation to this study.
Compliance with Ethical Standards
Conflict of interest
The authors declare that they have no conflict of interest.
- 1.Wyatt, R.: Review of existing data on underwater sounds produced by the oil and gas industry. In: Joint Industry Programme on Sound and Marine Life, London (2008)Google Scholar
- 2.Illinworth and Rodkin Inc.: Compendium of Pile Driving Sound Data. Illinworth and Rodkin Inc., Petaluma (2007)Google Scholar
- 4.Richardson, W.J., Greene, C.R., Malme, C.I., Thomson, D.H.: Marine Mammals and Noise. Academic Press, San Diego (1995)Google Scholar