An acoustical view of the sea: From ocean
acoustics to acoustical oceanography
Herman Medwin, Ph.D.
Ocean Acoustics Associates
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 todays successes in
applying these physical acoustics methods at sea, and try to predict tomorrows 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.
coral reefs of Tasmania- Community structure, impacts of trawling, and conservation
Last updated: December 19, 2000