GOOD things come to those who wait.

The dogged research by acoustics expert Professor Steven Cox has resulted in an oil tank in the Highlands being recognised by the Guinness Book of Records as having the world's longest echo (an echo is caused by the reflection of sound waves from a surface back to the listener).

Mr Cox climbed into the giant underground container, 30ft wide and more than 44ft high, in an 80-year-old oil storage complex at Inchindown, near Invergordon, and began singing and shouting. The echoes lasted 75 seconds, a full one minute longer than the previous record, held by Lanarkshire's Hamilton Mausoleum.

The results were verified when archaeological investigator Allan Kilpatrick fired a pistol loaded with blanks about one-third of the way into the storage tank while Mr Cox recorded the response picked up by the microphones about one-third of the way from the far end.

The tests were a culmination of Mr Cox's quest to find the world's "most reverberant" spaces while researching his new book, Sonic Wonderland: A Scientific Odyssey of Sound.

Good things come to those who wait.