Early Warning: Acoustic Radar

Image: Sound Mirrors near Dungness, Kent, UK

Scattered around the South East coast of England are these concrete objects. They are Acoustic Mirrors, built from 1916 to the mid 1930’s as an acoustic early warning system . The mirrors were simply large ‘acoustic ears’ used to locate approaching enemy aeroplanes and Zeppelins by amplifying and pinpointing engine sound – they had a range of around fifteen miles which gave a few minutes extra warning over visual location . The parabolic mirrors reflected and focussed the sound into one spot which was picked up by the listener through a rubber tube attached to the ears – a great example of the practical application of British exentricity. The mirrors eventually became obsolete with the development of faster aircraft and killed off entirely with the invention of Radar.

Mobile versions of the sound mirrors were still in use by Germany, Briatain and the USA during the Second World War as crude anti aricraft warning devices:

Image: German Acoustic Early Warning device 1940s

Image: British Acoustic Early Warning device 1940s

Image: Japanaese Mobile Acoustic Horns 1930s

Link:

Sound Mirrors on the SE coast

Acoustic Location and Sound Mirrors.

The Sound Mirrors project