An acoustical view of the sea: From ocean acoustics to acoustical oceanography

Herman Medwin, Ph.D.
Ocean Acoustics Associates
Emeritus Professor,
Naval Postgraduate School

Wednesday, September 15, 1999
3:00 p.m.—Pacific Forum

My purpose is to give a view of the sea from the perspective of a physical acoustician, who became an acoustical oceanographer. My journey has taken me from ocean acoustics, which describes sound propagation, to acoustical oceanography, which uses sound to deduce detailed ocean characteristics. I look at some of today’s successes in applying these physical acoustics methods at sea, and try to predict tomorrow’s uses and technological needs.

The methods of acoustical oceanography thrive on the spatial and temporal variability of the ocean. In the past 20 to 30 years, passive and active ocean acoustic characteristics have been inverted to understand the physical and biological sources of background sounds, ranging from rainfall to whales. We discuss some of the tools for acoustical inversions: careful experiments at sea and/or in the laboratory, as well as mathematical-physical descriptions of wave phenomena, such as speed of propagation, dispersion, refraction, facet reflection, wedge diffraction, absorption, doppler effect, and body resonances.

Next: Seamount coral reefs of Tasmania- Community structure, impacts of trawling, and conservation