Date | 10 February 2013 | ||
Location | Abbot’s Cliff, Folkestone, Kent | TR 27188 38605; 51.10170°N, 1.24369°E | |
Information |
Before the advent of radar, there was an experimental programme during the 1920s and 30s in which a number of concrete sound reflectors, in a variety of shapes, were built at coastal locations in order to provide early warning of approaching enemy aircraft. A microphone, placed at a focal point, was used to detect the sound waves arriving at and concentrated by the acoustic mirror. These concrete structures were in fixed positions and were spherical, rather than paraboloidal, reflectors. This meant that direction finding could be achieved by altering the position of the microphone rather than moving the mirror. The acoustic mirror at Abbot’s Cliff is located on the cliff top almost midway between Folkestone and Dover. Acoustic mirror (Wikipedia);
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Very good Graham!
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Thanks, Lita!
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These were an odd technological dead end inasmuch as they kind of worked (if the aircraft were close), but then radar came along not long after which was much more effective. Still, they’re interesting things to see, and there seem to be quite a few left!
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Yes, but behold the wonderfully bizarre looking related personal listening devices:
and so on…
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Awesome! Not quite as compact or discrete as your common-or-garden NHS hearing aid, but technological progress has to start somewhere.
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Fascinating! – I hadn’t heard of the acoustic mirrors before….
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Many thanks for stopping by!
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A wild idea…a long way away from the sensors available to the military today! I love the whackiness of this, and that these structures have lasted, to be adorned with the white noise of graffiti..
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Yes, technology has come a very long way since then
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Fascinating. A technological dead end of which I was unaware despite an interest in military aviation.
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Thanks for stopping by, Mark
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¡Que belleza!, aquí tenemos un sitio muy parecido
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Gracias, Manoli!
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What a fascinating piece of history.
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Many thanks for stopping by!
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I have read about these sound mirrors, so it is good to see such clear photographs of one – thank you for pointing me in this direction 🙂
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Very glad it was of interest!
🙏✨
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