A Sonar Phenomena: Acoustic Shadows

Sometimes more information can be gleaned from an acoustic shadow than from the object itself. Just as the sun casts a shadow, sound also casts a shadow. And just like with the sun, the shape and size of the shadow depends on the object and the angle of the sound beam hitting the selected object. In these two examples, details about the shapes of the fish can be easily seen. Some additional examples include: Giant Grouper, Turtle, Murray Cod.

A line of fish and their acoustic shadows swim past the sonar. Courtesy of Kevin Boswell, Dept of Oceanography and Coastal Sciences, LSU, Baton Rouge, LA

A large shark in the Dry Torgugas casts an informative acoustic shadow. Courtesy of Eric Steimle, University of South Florida

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