Sound Mirrors in Dungeness | image courtesy: Bill Allen
From Sun Tzu1 and the 6th century B.C., Eastern and Western world used “The Art of War” as the bible of the warfare. “Speed is the essence of war; travel by unexpected routes and strike him, where he has taken no precaution”, Sun Tzu writes. Even if technology has evolved, speed has been one of the most important elements in war times, evident or silent. With the invention of aircrafts, the need to anticipate an attack from the sky and the need of air-defence was significantly raised. Since technology was not as much sophisticated and computerized, and predictions concerning the position or the proximity of the enemy's aircraft weren't accurate, detection was possible simply by visual spotting, decoding of birds, animal's behaviour or even trees' movement. It was then that sound and listening became the most advanced radars, with high efficiency both during daytime and night-time. This is probably the main reason that sound culture became quite popular during Word War I.
Around 1914 a series of different acoustic devices were created by the British, the Dutch, the French as well as the Japanese army as early 'radars'. Today we are talking about hacking technology as a process towards innovative and refined evolution. But was the creation of such devices really a result of the same anticipation, substituting the human listening ability with regard to understanding time, volume, speed and distance, by hacking the ear?
"Topophone", by Prof. Alfred M. Mayer - 1880 | image from issue of Scientific America
The pursue of a “super ear” that was able to track objects much further than the ear's capturing radius, and a programmed mind that was able to process the information and locate it in significant accuracy, have a long history behind them. Early appearances of “cyborgs”2, if we may call them that, were long before the appearance of the term in 1960 in an article by Manfred Clynes and Nathan S.Kline “Cyborgs and Space”3, making their depute in about 1880 with the so-called “topophone”. Invented by Professor Alfred M. Mayer in the United States, the topophone was a device for measuring wavelength and velocity, of sound in gases. Prosthetic applications of similar kind of tech attributes, started to become more and more relevant in WWI, specially in Europe.
Depending on the geometry, material, size and directional possibilities of each invention, each listening equipment had different levels of accuracy towards approaching aircrafts and their position, always relying on weather conditions and of course the skills of the operator.
"Waalsdorp", acoustic locator of the Dutch Army | image courtesy of Waalsdrop Museum
"War Tuba", acoustic locator in the Japanese Army | image source Wikipedia
In the Dutch Army acoustic locator devices were made out of metal, the most known being called “Waalsdorp”, an acoustic locator attached to the human body and in direct fitting to the ear, aiming to expand the radius of its sound perception. According to the Museum of Waalsdorp's explanation, “the adjustment of the chart angle in the horizontal plane around the column, took place by muscle force of arms and legs. Great care was devoted to the smooth and noiseless operation of this vertical bearing without play or backlash.” In Japan, acoustic locators were detached from the human body, mostly resembling the music instrument “tuba” and were “typically consisted of large acoustic horns attached to stethoscope-type earphones worn by monitors”,(source: Wikipedia). However, from the small devices that could be adjusted to the human body, the continuous experiments and research, resulted to some large-scale parabolic structures, constructed out of reinforced concrete, reaching even 10 meters in height.
Sound Mirrors Acoustic Technology | courtesy of the Sound Mirror Project
Sound Mirror in Dungeness, UK, back view | image source talkphotography.co.uk
Sound Wall 60mX10m in Dungeness, UK, back view | image source: roumazeilles.net
In England, there were three main types of acoustic devices: mirror, wall and disc. Initially operated by the human ear, the listener was at the end course of a rubber tube, whilst at the other end a second cone was gathering sound information from the mirror. In fact, that was the case until the appearance of microphones. British experiments at the Royal Flying Corps Research Establishment at Farnborough tested parabolic acoustic sound reflectors of varying shapes and curvature, and led to the first true sound mirror at Binbury Manor in the summer of 1915.
Sound Mirror at Abbot's Cliff looking west | image by: Eric Jones | image source
Whereas the acoustic locator devices described above may trigger our interest in mechanics a lot more, the sound mirrors seem to provoke a more scientific interest on acoustics. Exploring the scientific aspects of structures like this, we might find intriguing to explore the “whispering gallery”4 effect, where one can whisper on one side of the room and be heard on the opposite side, an aftermath achieved by placing two concave parabolic sound mirrors facing each other. The effect was discovered not long before the sound mirrors, by Lord Rayleigh in St. Paul's Cathedral's Whispering Gallery.
St. Paul's Cathedral's Whispering Gallery | image by : Henry Grant | courtesy of: Museum of London
In the art scene the possible communication aspect of these structures, inspired artist Lise Autogena, who transformed the sound mirrors in the UK coast as the portal of communication over the sea, between England and France. The project is about constructing two new sound mirrors that will face each other across the English Channel, and will permit an over sea communication between the French and the English,(ongoing since 1998).
Sound Mirrors project geography | image courtesy of The Sound Mirrors project
A nice view of the sound mirrors in UK can be viewed In the official videoclip of Prodigy's song "invaders must die" at 1:20'
article references and terminology:
1. Sun Tzu: a Chinese military general, strategist and philosopher who lived in the Spring and Autumn Period of ancient China, author of “The Art of War”. 2. Cyborgs: Beings with both biological and artificial parts, whose abilities have been enhanced due to the presence and advancement of technology. 3.“Cyborgs and Space”, article by Manfred E. Clynes and Nathan S. Kline. 4.Whispering gallery waves are a type of wave that can travel around a concave surface.