Kilnsea Sound Mirror


A sound mirror or acoustic mirror is a passive device used to reflect and perhaps to focus (concentrate) sound waves. They were used during World War I as an anti-aircraft early-warning device prior to the introduction of radar. A wide network of large acoustic mirrors was in the process of being set up in southern England when the project was suddenly cancelled as the Chain Home system evolved.

Acoustic mirrors had a limited effectiveness, and the increasing speed of aircraft in the 1930s meant that they would already be too close to deal with by the time they had been detected.

The development of radar put an end to further experimentation with the technique. Nevertheless, there were long-lasting benefits. The acoustic mirror programme, led by Dr William Sansome Tucker, had given Britain the methodology to use interconnected stations to pin point the position of an enemy in the sky. The system they developed for linking the stations and plotting aircraft movements was given to the early radar team and contributed to their success in World War II, although the British radar was less sophisticated than the German system, the British system was used more successfully.

On the East Yorkshire Coast just outside Kilnsea can be seen a fine example of a acoustic sound mirror. The microphone stand in front of the mirror is still in situ which would have fed sounds back to a listening operator. The dish itself is around 15 feet in diameter and the whole structure dominates the skyline from the road as you travel towards Spurn. We don't know how long this will be here, it has sat for the last 100 years in splendid isolation but the threat of coastal erosion one day will take it onto the beach to join the rest of the East Coasts Defence crust.


Sat proudly looking out to sea


Fenced off to keep her safe


A relic of a simpler age


The microphone stand


Panorama shot in all it glory