Approved for public release. Distribution unlimited.
 Editor's note: The author is on the staff of the Dean of the College of Ocean and Fishery Sciences, University of Washington, Seattle, but is presently on detail to the Naval Sea Systems Command, PMS 435, Washington, D.C.

As explorationists know, sound is commonly used to investigate and understand phenomena in the ocean and the structure of geologic strata beneath the sea. But, as they may not know, it is also used by submarines and surface ships to find and track other submarines and ships. In all cases, the sound is detected and recorded...

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