Acoustic early warning systems, spectacular remnants of a dead-end technology on the British coast
“Listing of sound mirrors urged: Oliver Gillie reports on the pre-radar detection devices that enthusiasts want to see preserved” from the Independent on 3 July 1993.
HUGE CONCRETE sound mirrors used before the days of radar to listen for the approach of hostile aircraft should be scheduled as national monuments, according to enthusiasts. Already several have been demolished …
Anyway I visited the mirrors to take some photos a few times around 1997 and 1998. At the time they were almost totally forgotten about and in the middle of an active gravel pit. The large 200 foot sound wall was very close to falling into the pit and disappearing forever. It was such a strange an eerie place…[More…]
Sound and Vision at Walking Class Hero: These other worldy concrete structures are the remains of part of an acoustic early warning system that was designed to detect engine sounds from approaching aircraft. ‘Staccato signals of constant information‘ as Paul Simon sings from another time
Another very popular walk, it seems: I stopped estimating at 150
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Listening Vessels consists of two large parabolic reflectors set at least 50 feet apart which act as mirrors to reflect sound from one to the other. Two people sit opposite each other at approximately the focal point for each reflector, so that the sound coming from each reflector is focused at this point, allowing each visitor to clearly hear the other’s voice, even at a very low decibel in spite of the distance separating the vessels.
Source: The Exploratorium
It would appear that the “War Heroes” episode of the television programme Great Railway Adventures With Dan Cruickshank featured the Denge sound mirrors.
Follow the white rabbit: Today we went to see the Sound Mirrors at Denge…
Zeppelin Airship Attacks On London: Mapped at Londonist.
Maltese telecoms firm GO has updated the kit at its Maghtab site, by the sound mirror:
In comments, [Prime Minister] Dr Gonzi said the Maghtab headend site was symbolically important because of the sound mirror, a primitive radar built some 70 years ago to detect and amplify the sounds of air and sea vessels nearing Malta.
This is the only sound mirror built outside England but became outdated within three to seven years since being built because it was replaced by radars.
Dr Gonzi said that even nowadays, major investment in technology became outdated quickly and companies needed to continue investing consistently.
GO fully equipped to transmit English and Italian football, Annaliza Borg, The Malta Independent
Lots of good pictures are appearing on Flickr after the 18 July 2010 open day at the Denge sound mirrors (click to see Richard Fisher’s picture in full):
Feel free you add your photos to the Sound Mirrors Pool.
Thread at the Kent History Forum.
