The Longest Echo in the World
A secret wartime fuel tank buried in a Scottish hillside holds the record for the longest echo: 75 seconds.
What was reported
Before the Second World War, the Royal Navy dug huge fuel tanks into a hillside at Inchindown, near the naval base at Invergordon, safe from bombing. The largest is about 237 metres long and 13.5 metres high, carved into solid rock.
In 2014 the acoustic engineer Trevor Cox squeezed in through a small pipe and fired a blank from a pistol. The sound took 75 seconds to die away, setting the Guinness record for the longest echo in a man-made structure.
Explanations offered
The tank's concrete walls are hard and smooth, and the vast, empty, sealed space lets sound bounce back and forth with almost nothing to absorb it. Low notes lingered even longer than the gunshot as a whole.
- When
- Record set in 2014
- Where
- Inchindown, near Invergordon, Highland, Scotland
- Witnesses
- The acoustic engineer Trevor Cox
- Status
- Explained
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