New world record for longest echo set near Invergordon

A new world record for the longest echo in a man-made structure has been set in an underground fuel depot constructed in Scotland before World War Two, the BBC reports.

Salford University acoustic engineer Prof Trevor Cox recorded a shot fired from a pistol loaded with blanks inside Inchindown tunnels near Invergordon.

The time for the reverberation to end was 112 seconds.

That beat the 1970 Guinness World Records time of 15 seconds set in Hamilton Mausoleum in Lanarkshire.

Allan Kilpatrick, of the Royal Commission on the Ancient and Historical Monuments of Scotland (RCAHMS) and an expert on Inchindown, fired the pistol, loaded with blanks, about a third of the way into one of the storage tanks.

Prof Cox recorded the response picked up by the microphones about a third of the way from the far end.

He said he was amazed by the acoustics inside the tunnels.

"Never before had I heard such a rush of echoes and reverberation," he said.

The acoustic engineer said this was a standard technique used in concert hall acoustics.

"My initial reaction was disbelief," he said. "The reverberation times were just too long."