Acoustic Defense: Photo Series Reflects on Derelict British “Sound Mirrors”

In the wake of World War I, the United Kingdom developed a powerful yet relatively low-tech architectural system for detecting incoming enemy airplanes, the remnants of which can still be found across the countryside.

Starting in the 1920s, these concrete sound mirrors would passively gather, reflect and concentrate acoustic waves, directing the sound to a listening post on the ground as part of an early warning alert system.

Incoming sounds were amplified by microphones and listened to by operators wearing headphones. Today, most are abandoned and in disrepair, though some are protected with walls and fences and/or accompanied by historical plaques.

Based in Basel, photographer Piercarlo Quecchia discovered the existence of sound mirrors thanks to an album cover featuring one such structure, and began the find and photograph them — 13 in total (all that remain), most of which can be found on the southern edge of England.

They may look monolithic and simple, but the curves were carefully calibrated. The designs were specifically calculated (and sound mirrors accordingly engineered) to pick up aircraft engine noises.

“They represent an incredible demonstration of how sound can generate a physical form: both the curvature radius and the dimensions of the dishes are studied and designed according to the sound frequency that they must reflect,” explains the photographer. He hopes the series will continue to raise awareness of these artifacts.