QuickTime (48K) Click this button to use any media player Sound courtesy of OSAP/IOS CANADA

Surface waves can be caused by several different sources, such as passing boats, wind, and rain. When a wave breaks, bubbles are formed within the surface water. The movement and breaking of these bubbles cause strong underwater sounds. Bubbles left by the wake of a passing ship can be identified for almost an hour after the event. Breaking waves entrain air bubbles that generate ambient noise. Ambient noise in the frequency range of 500-100,000 Hz is mostly due to spray and bubbles associated with breaking waves. It increases with increasing wind speed.

References
• Medwin, H. 1995. Measurement of Passive and Active Microbubbles in the Sea. Acoustical Society of America Meeting , St. Louis, Missouri, November 1995.

Additional Resources
• Deane, G.B. and Stokes, M.D. 2002. Scale dependence of bubble creation mechanisms in breaking waves. Nature 418 (22 August 2002): 839-844.
• Institute of Ocean Sciences/Acoustical Oceanography Research Group: Breaking Surface Waves
• Institute of Ocean Sciences/Acoustical Oceanography Research Group: The Surf Zone
• Nystuen, J.A. and Ma, B. 2002. Using Ambient Sound to Passively Monitor Sea Surface Processes. Pan Oceanic Remote Sensing Conference, Bali, Indonesia, September 2002.