Denge’s Concrete Ears
Wednesday, 10th September 2008 by James Turnbull
Way back in the 1910s and 20s, before radar had become a useful technology, Britain needed a way to try and detect incoming enemy aircraft. The solution was to build enormous concrete “listening ears” around the south coast of Britain, whose purpose was literally to “hear further”.
The most famous examples of these “acoustic mirrors” are the three at the former Royal Air Force base of Denge. The largest is more-or-less just a 60 m long curved wall.
The smaller two mirrors however, more closely resemble large satellite dishes on pedestals.
Believe it or not, the “listening ears” did actually work, although they were rather prone to error, due to it being difficult to hear the difference between incoming aircraft and passing boats.
As aircraft got faster, using the dishes as a warning system became much less practical, and when radar eventually matured, the huge listening ears were permanently discontinued.
Lots more information and ground level pictures on Andrew’s sound mirror page.
Thanks to jono.