These Acoustic listening devices were developed for the Dutch army as part of air defense systems research between World Wars 1 and 2. Made me look! Oh my!
I’d really love to hear what they sound like.
Brilliant! I wonder how successful they were. Or if they were the equivalent of two huge sea shells.
this is related to the sound mirrors in the uk, forerunner of the radar. really impressive stuff ! http://bit.ly/5VViZj
No wonder we got beat-up in high-school.
Oh yes, my collegue needs these.
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