Pages about acoustic mirrors

History and technology

• There is a history of the south coast sound mirrors by Phil Hide at the Cantiaci Time Team Forum Friends website.
• Sound Mirrors on the South Coast at ourpasthistory.com. Certainly the mirrors at Fan Bay, Dover (also identified as Langdon) and Joss Gap near North Foreland saw action in 1917 and 1918, the Fan Bay mirror detected an enemy raid at a range of 12-15 miles in October of 1917 and in 1918 both mirrors were able to detect aircraft heading for London several minutes before they were audible to the unaided ear.
• Before radar – acoustic detection of aircraft. The system was effective in principle and the large parabolic dishes focussed the incoming parallel sound ‘rays’ to a single point at which a listening device could be positioned. In calm air conditions a range of about 15 miles (25 km) could be achieved but the speed (350 kph) of the aircraft in existence when the system was eventually abandoned was such that only about 4 minutes warning of approach could be given.
• Acoustic Location and Sound Mirrors. Weird and wonderful portable and static ones from around the world at the Museum of RetroTech.
• Listening for the Enemy by Brian Dillon at Cabinet, a quarterly magazine of art & culture. Eight decades after De Quincey described his acoustic epiphany, in a room of the Post Office building in Carter Lane, between St. Paul’s and the River Thames, representatives of the Air Defence Experimental Establishment awaited telephoned reports of aircraft noise from a series of listening posts which had begun to dot the coast of south-east England—a scattering of modernist whispering galleries where ears were trained not on the deep past but on the immediately threatening future, the increasing likelihood of German bombing or invasion from the air.
• Hythe Sound Mirrors [and Denge] from Southdown Amateur Radio Society. During a conversation at work one day, the subject of Dishes at Greatstone came up. This took me back to 1980, while on holiday there. From what I remember, some unusual looking parabolic dishes not too far away from the holiday site could be seen, so I went to investigate.
• The Sound Mirrors: A History of the Future of War Noises by Ithamar Silver, Le Panoptique, July 2008. The Sound Mirrors may seem laughably naive — a misguided, stone-age radar out of The Flintstones — yet this primitive technology was actually an imaginative and moderately successful response to the unfamiliar threat of the warplane.

Photos

• There is a Flickr sound mirrors pool which you are welcome to add your sound mirror photographs to.
• The White Cliffs Underground site has photographs of the ruined mirror at Warden Point on the Isle of Sheppey, the mirror east of Folkestone at Abbot’s Cliff, and at Langdon Bay east of Dover, as well as the Lade (Dungeness) mirrors and wall.
• The Denge sound mirrors at Citynoise.
• Simon Wood’s photographs of sound mirrors.

Sound mirror art

• “An ambitious project to create a unique cross-Channel communications link via sound mirrors” at Folkestone and Sangate is mentioned in a Shepway District Council press release of 2003-07-22: Sound Mirror Site Visit Reflects Entente Cordiale.
• Return of sound mirrors that trapped Zeppelins, a report on the art project from the 2001-01-29 Daily Telegraph.
• More from the Arts Council
• Turin Brakes and Blank & Jones have used pictures of the Denge mirrors on some CD covers.
• Sound Mirrors by Tacita Dean. 1999, 16mm black and white, optical sound, 7 mins. The soundtrack to this film is entirely recorded within the 200 ft mirror at Denge.

Peaceful sound mirrors

• There are reported to be some modern sound mirrors used to explain reflection and diffraction of sound at Jodrell Bank Visitor Centre.

Related topics possibly of interest

• SouthEast Defence Photos. Photographs of a vast range of different types of military architecture which existed and still exists in Southern England.
• The Defence of East Sussex Project is the most comprehensive post-war survey of the anti-invasion defences of the county using original archive documents.
• Some photos I took of a World War II bombing decoy near Kingston upon Hull.
• The Defence of Britain database has records of the 20th century militarised landscape of the United Kingdom.
• The Pillbox Study Group website.
• World War II pillboxes and anti-invasion defences.
• Everything you might want to know about Martello Towers. … the army of Napoleon Bonaparte was camped at Boulogne, ready to launch an invasion across the English Channel. It was decided to build circular brick towers, each mounting a cannon on the roof, along the vulnerable coastlines of Sussex and Kent.