The Greatstone Sound Mirrors, massive concrete listening devices shaped like crude ears, were built in marshland in Kent in the late 1920s as part of Britain’s national defence strategy. The ears pointed towards the European mainland.
They look a bit like stone age satellite dishes, though a bit harder to move about.
The ears were an attempt to “hear” approaching enemy aircraft. Sound waves generated by anything flying towards them were captured in these huge concrete bowls, then relayed back through microphones and (in a glorious Heath-Robinson touch) a stethoscope to an operator who would raise the alarm.
These massive ears effectively gave Britain a fifteen-minute warning of an impending attack.
It seems mad but they actually worked, though they couldn’t tell the difference between various aircraft. A squawking bird, and innocent jaunt in a biplane with a picnic hamper in the back seat or an excursion in one of those motorised balloons would sound the same as something considerably more threatening. They’re a Dad’s Armyish idea – like Godfrey’s ears.
There were some portable versions too:
And some slightly less portable:
The creation of better, faster aircraft made them less useful, as an incoming aircraft would be within sight by the time it had been located. Growing levels of ambient noise also made the mirrors more difficult to use successfully. Soon radar made acoustic detection redundant.
They are huge. There is a 20ft vertical saucer, a 30ft bowl, tilted to the sky, and a mammoth 200 ft long strip mirror.
It’s a fantastic example of the application of creativity to solve a problem that lacked a technical solution. You can imagine the discussions leading up to it and the “it might just work” moment. I love the coconut shell experimentation of it, married with the scale.
The other thing that struck me was the idea that, even then, in the sedate Thirties, ambient noise got in the way. Imagine how much noise would interfere today. A fancy dress barbecue with mobile disco chez Farages in Kent might set off Britain’s national defences. Now there’s a thought.
Ambient noise and distractions really are a contemporary curse. Filtering through all that we are exposed to and pinpointing the things that really matter is very hard indeed. As communicators, we’ve become accustomed to the blunderbuss approach, hoping for what we call ‘traction’, and losing touch in the process of what really matters to the recipient.
We’ve come to associate ‘reach’ with numbers rather than outcomes. It’s worth pausing and considering what the recipient, the individual, might want to hear – and more importantly, why. The art is in saying something that will make people sit up an listen. Otherwise we are liable to get lost in the sea of noise.