A sound mirror (or acoustic mirror) is a device employed to reflect and concentrate sound waves. An experimentation on large scale acoustic mirrors has been run after WWI in Great Britain to detect incoming enemy aircrafts taking off on the other side of the English Channel. By enhancing the sound of enemy aircraft’s engines, the mirrors would have enabled the British defense to detect incoming airplanes fifteen minutes before they were visible.
Built between 1927-30, the sound mirrors were part of Britain’s national defense strategy, but they became rapidly obsolete due to the rapid increment in speed of the aircrafts and the invention of radar. The most famous examples of acoustic mirrors are preserved in Denge on the Dungeness peninsula in England. Three different kinds existed: two made of dishes of different proportions and one, a 70 m long curved wall. Headphones were placed at the foci of the reflectors enabling a listener to detect the sound of an aircraft.
Several videos have been produced in more recent times with the aim of documenting the ghost-like presence of these abandoned monoliths and the sound they reflected; one is ”Blackout (The Antiphony Video Supplement)” by Barry Hale (1997), a video produced as part of a project by the sound art collective Disinformation (Joe Banks); another is the 1999 short film by Tacita Dean entitled “Sound Mirrors“.
More human-scale examples of sound mirrors spread across Europe in the interwar period: instead of heavy and static concrete constructions, transportable steerable horns or personal/wearable horns were adopted for the passive detection of aircrafts. Further, accurate informations are available here.
We can only imagine, had these machines ever been used, the profound effect they could have had on their users. Speculating on the possible experience of the listener, we can suppose he was completely absorbed in a state of deep concentration and even morbid expectation for an upcoming, probably destructive event (the arrival of war machines). We can only imagine the utterly overwhelming sense of loneliness intrinsical in the possibility of ”anticipating time”, of being in one place, yet sensorily detached from it: the expansion of hearing providing sensory deprivation from the immediate human scale.
Although these devices were rapidly written off in favour of more advanced technologies like radar, their “artistic”, speculative implications somewhat seemed to survive throughout the 1960’s and the 1970’s, when analogical apparatuses were conceived by radical artistic/architectural collectives for the purpose of the expansion of human perception, arguably with the accompaniment of lysergic drugs.
We’d like to think that a latent, obscure link exists between the original wartime sound mirrors and 1967-69 Haus Rucker Co.‘s “Mind Expander Program”, a series of performative-architectural sculptures equally aimed at a sensory deprivation and expansion/distortion. As brilliantly explained by the author of Data is Nature, these helmet-like enclosures “create a space for intimate introspection and hyper-awareness via sensory deprivation. It’s also a simple metaphor for the removal of oneself from consensual reality. Liberated from external distractions the user journeys inwards to generate personalised sensory impressions of their own.”
Images of sound mirrors in Denge from:
Further read about static -concrete- sound mirrors:
About portable acoustic devices:
About Haus Rucker Co: