Acoustic locators

Acoustic location is used to determine the location and direction of movement of bodies. At the beginning of the 20th century, a number of unusual gadgets were constructed to enhance the capabilities of the human ear, some of which can be viewed under the cut.


Made by Czechs in the 1920s



Such a device was used by the Dutch military.
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But the United States owned it.

Sources (there are still a lot of interesting pictures):
www.dself.dsl.pipex.com/museum/COMMS/ear/ear.htm
www.museumwaalsdorp.nl/en/firstwk.html
butdoesitfloat.com/190819/For-the-world-to-be-interesting-you-have-to-be-manipulating-it-all