Now we've heard it all: Acoustic scientists shatter the world record for longest ever echo


Deep inside a complex of secret tunnels in the Highlands stirs a sound which will reverberate through the ages. The world record for the longest echo ever discovered has been shattered by a hidden network of oil storage tanks in Rossshire.

Acoustic scientists emerged from the Inchindown oil storage tanks, an underground fuel depot constructed during World War II, with proof that a gun-shot fired inside the tunnel resonates for a full 112 seconds.

The discovery marks a resounding defeat for the previous record-holder for the longest echo found in a man-made structure, the Hamilton Mausoleum, also in Scotland, where the sound of the doors being slammed shut took 15 seconds to die away to silence.

Guinness World Records has certified the findings made by Trevor Cox, Professor of Acoustic Engineering at the University of Salford and author of Sonic Wonderland: A Scientific Odyssey of Sound.

Prof Cox had received a tip that the Inchindown complex near Invergordon might prove fertile territory for an echo test.

Excavated out of solid rock between 1939 and 1941, the tanks were dug deep into the hillside amid concerns about the strengthening of Germany's armed forces and the threat posed by long-range bombers.

The tunnels were to provide a huge bomb-proof reserve supply of furnace oil for the warships of the home fleet at Invergordon, a key Royal Navy anchorage.

Prof Cox had to enter the tank through one of the 18 inch diameter oil pipes because there are no doors. The tank was designed to hold 25.5 million litres of fuel and has walls 45 cm thick. The space is about twice the length of a football pitch, 9m wide and 13.5 metres high.

Allan Kilpatrick, an archaeological investigator for the Royal Commission on the Ancient and Historical Monuments of Scotland, fired a pistol loaded with blanks about a third of the way into the storage tank. The results stunned Prof Cox, who recorded the response picked up by the microphones about a third of the way from the far end.

"It was like going underground into a Bond villain's lair. But never before had I heard such a rush of echoes and reverberation," Prof Cox said. "I started off just playing around, whooping and hollering. The sound just goes on and on and on."

"Then when we fired the pistol my initial reaction was disbelief; the reverberation times were just too long. I knew immediately we had a new world record."


At 125 Hertz, a frequency typically made by a tuba, the reverberation time was 112 seconds. Even at the mid-frequencies important for speech, the reverberation time was 30 seconds.

The broadband reverberation time, which considers all frequencies simultaneously, was 75 seconds – the figure certified as a world record by Guinness.

Inchindown's six tanks were reportedly at full capacity during the Falklands War in 1982 but the depot was decommissioned and closed in 2002.

Prof Cox said the tunnel's extraordinary resonance could be incorporated into a musical composition, although the pipes are only accessible through limited guided tours.

"There are no doors so I had to be pushed in through the 18-inch diameter pipe. I threw my clothes away when I got out. Every surface was covered in oil. But you could play whole melodies with your voice, singing chords to yourself.

"Reverberation is central to classical music," he added. "The notes hold for so long do you make meditative whale music, playing really slow notes. Or do you play fast and create a smog of dissonance? It would be interesting to write a piece of music to the pipes."

Prof Cox was tipped off about Inchindown after the structure featured on BBC1's The One Show. It delivered the perfect conditions for reverberation. "You need a man-made structure with no windows and a smooth concrete surface with pores to absorb sound. I didn't think we'd find anything as reverberant as this."

Sound Effects: Typical reverberation times at mid-frequency

  • Living room: 0.4 seconds

  • Opera house: 1.2 seconds

  • Concert hall for classical music: 2 seconds

  • St. Paul's Cathedral: 9.2 seconds


  • The loudest purr of a domestic cat (67.7 decibels)

  • The loudest burp by a male (109.9 decibels)

  • The loudest clap (113 decibels)


Start your day with The Independent, sign up for daily news emails
Life and Style
Arts and Entertainment
The Ridiculous Six has been produced by Adam Sandler, who also stars in it
filmNew controversy after nine Native American actors walked off set
Ed Miliband, Nick Clegg and David Cameron appeal to the audience during the Question Time special
Danny Jones was in the Wales squad for the 2013 World Cup
rugby leagueKeighley Cougars half-back was taken off after just four minutes
Life and Style
Google celebrates Bartolomeo Cristofori's 360th birthday
techGoogle Doodle to the rescue
Life and Style
The original ZX Spectrum was simple to plug into your TV and get playing on
techThirty years on, the ZX Spectrum is back, after a fashion
ebooksA celebration of British elections
  • Get to the point
Latest stories from i100
Have you tried new the Independent Digital Edition apps?
Independent Dating

By clicking 'Search' you
are agreeing to our
Terms of Use.

iJobs Job Widget
iJobs General

Recruitment Genius: Senior Digital Marketing Consultant

£28000 - £45000 per annum: Recruitment Genius: A Senior Digital Marketing Cons...

Recruitment Genius: Assistant Stores Keeper

£16640 - £18500 per annum: Recruitment Genius: An Assistant Stores Keeper is r...

Recruitment Genius: Claims Administrator

£16000 - £18500 per annum: Recruitment Genius: This is an excellent opportunit...

Recruitment Genius: Software Developer - C# / ASP.NET / SQL

£17000 - £30000 per annum: Recruitment Genius: Developer required to join a bu...

Day In a Page

Fishing for votes with Nigel Farage: The Ukip leader shows how he can work an audience as he casts his line to the disaffected of Grimsby

Fishing is on Nigel Farage's mind

Ukip leader casts a line to the disaffected
Who is bombing whom in the Middle East? It's amazing they don't all hit each other

Who is bombing whom in the Middle East?

Robert Fisk untangles the countries and factions
China's influence on fashion: At the top of the game both creatively and commercially

China's influence on fashion

At the top of the game both creatively and commercially
Lord O’Donnell: Former cabinet secretary on the election and life away from the levers of power

The man known as GOD has a reputation for getting the job done

Lord O'Donnell's three principles of rule
Rainbow shades: It's all bright on the night

Rainbow shades

It's all bright on the night
'It was first time I had ever tasted chocolate. I kept a piece, and when Amsterdam was liberated, I gave it to the first Allied soldier I saw'

Bread from heaven

Dutch survivors thank RAF for World War II drop that saved millions
Britain will be 'run for the wealthy and powerful' if Tories retain power - Labour

How 'the Axe' helped Labour

UK will be 'run for the wealthy and powerful' if Tories retain power
Rare and exclusive video shows the horrific price paid by activists for challenging the rule of jihadist extremists in Syria

The price to be paid for challenging the rule of extremists

A revolution now 'consuming its own children'
Welcome to the world of Megagames

Welcome to the world of Megagames

300 players take part in Watch the Skies! board game in London
'Nymphomaniac' actress reveals what it was really like to star in one of the most explicit films ever

Charlotte Gainsbourg on 'Nymphomaniac'

Starring in one of the most explicit films ever
Robert Fisk in Abu Dhabi: The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers

Robert Fisk in Abu Dhabi

The Emirates' out-of-sight migrant workers helping to build the dream projects of its rulers
Vince Cable interview: Charging fees for employment tribunals was 'a very bad move'

Vince Cable exclusive interview

Charging fees for employment tribunals was 'a very bad move'
Iwan Rheon interview: Game of Thrones star returns to his Welsh roots to record debut album

Iwan Rheon is returning to his Welsh roots

Rheon is best known for his role as the Bastard of Bolton. It's gruelling playing a sadistic torturer, he tells Craig McLean, but it hasn't stopped him recording an album of Welsh psychedelia
Russell Brand's interview with Ed Miliband has got everyone talking about The Trews

Everyone is talking about The Trews

Russell Brand's 'true news' videos attract millions of viewers. But today's 'Milibrand' interview introduced his resolutely amateurish style to a whole new crowd
Morne Hardenberg interview: Cameraman for BBC's upcoming show Shark on filming the ocean's most dangerous predator

It's time for my close-up

Meet the man who films great whites for a living