Silence doesn’t exist. Even in the quietest corners of our planet, there are always sounds. At the summits of the calmest mountains, you’ll invariably still hear a faint whistle of wind. In the centres of the grandest, most motionless forests, there will always be a distant crack of a branch. In Britain – home to 67 million noisy people – silence has become one of our most precious commodities. 

You’d suspect it would be near impossible to find on these busy shores, but within just minutes of touching down on Foula – one of our most remote inhabited islands, some 20 miles west of mainland Shetland – I could hear just a few, barely audible waves, grumbling over a soundscape of nothingness. Silence,...