What is the mysterious 'Largs Hum'?

For at least four decades, a number of residents of the pretty west coast town of Largs have complained of an unexplained deep droning sound that causes everything from sleeplessness and headaches to teariness and absolute despair.

For decades, some residents of Largs on the Firth of Clyde have reported being plagued by a low, unexplained droning sound which has been dubbed the "Largs Hum". PIC: Dave Souza/Wikipedia/Creative Commons.

Dubbed the Largs Hum, the phenomenon has divided opinion. Some say it is a figment of the imagination to those who claim to have been afflicted by it. Others - and it has not confined to Largs, with similar cases reported around world - say it has ruined lives and forced them to to move from their homes.

One woman, - Georgie Hyslop - left Largs and hit the road in a caravan, such was her belief the hum was seriously impacting on her health.

Cases of the Largs Hum have frequently been reported in the Largs and Millport News and in 2009, Ms Hyslop tols the newspaper the sound got worse as darkness fell.

In 2009, she told a newspaper: "You dread the night. During the day at least you can get out and make a noise."

It was said the hum scrambled her radio and television. At best it caused a sore head but popping ears, chest tightness, memory loss, nausea and sickness were also endures, according to Hyslop.

Earlier this year, the Largs Hum was still making column inches in the Largs and Millport News.

Connor Connor Welsh, 24, told the newspaper: "I first heard this noise which was quite low pitched and quiet.

"I had a look around the back garden and tried my best to find the source of it but there was nothing there.

"The second time I heard it I had been sleeping and it woke me because it was quite loud.

"I first heard this noise which was quite low pitched and quiet.

"I had a look around the back garden and tried my best to find the source of it but there was nothing there.

"The second time I heard it I had been sleeping and it woke me because it was quite loud.

"We heard it on and off for a good month and then nothing."

Other Largs residents came forward to tell their experiences of the hum as a result of Connor's recording. One woman said it sounded like her heating was still on - when it wasn't.

Testing carried out at Ms Hyslop's by Glasgow Caledonian University found a frequency of between 50 and 60Hz - one or two octaves above normal human hearing - according to a newspaper report.

Residents in cities including Bristol, Vancouver and Auckland have reported similar mysterious sounds and sensations, which remain largely unexplained.

Various factors have been suggested as the cause, including gas pipes, mobile phone masts, wind farms, nuclear waste, and low-frequency submarine communications - but no definitive cause has been found.

In Kokomo, Indiana, the mystery was partially solved. The source of "the hum" was located to a fan and a compressor on an industrial site - but some said the noise continued even after the kit was turned off.

Expert Geoff Leventhall, a noise and vibration consultant who has advised the government on the issue. Once, he detected a 200 hertz signal to the home of a complainant's neighbour. The source was identified as a central heating system.

Some experts say that it is tinnitus to blame although those who claim to hear the hum often dispute this.

In 2009, Dr David Baguley, head of audiology at Addenbrooke's Hospital told the BBC that in about two thirds of 'hum' cases no external noise could be found and that the hearing of sufferers had become over-sensitive.

"It becomes a vicious cycle. The more people focus on the noise, the more anxious and fearful they get, the more the body responds by amplifying the sound, and that causes even more upset and distress," he said.

The only thing certain about the Largs Hum - and other cases like it - is the mystery continues for many.