Tom Scott did a video about another acoustic lens: the "sound mirror" overlooking the English Channel that was intended to be an early warning against aircraft

Tom Scott did a video about another acoustic lens: the "sound mirror" overlooking the English Channel that was intended to be an early warning against aircraft coming from the continent. https://www.youtube.com/watch?v=04F5osXK4vw https://www.youtube.com/watch?v=04F5osXK4vw