Council discovers source of low hum that is driving residents crazy - but now they're refusing to tell anyone what it is

Noise experts have finally identified the source of a low-level hum that has been keeping the residents of Omagh up at night for months - but the culprit can't be named for legal reasons.

Last August, a group of perturbed residents from the town in County Tyrone, Northern Ireland began complaining about a persistent humming noise.

Fermanagh and Omagh District Council said it's environmental health service went on to receive a further 10 complaints up to April of this year.

Conspiracy theories about what was causing the noise - that one resident says 'went on for hours and hours' - began to spread far and wide.

The council eventually commissioned a noise consultant to find the cause, with the council admitting in June the search had been 'complex', but the specialists had been able to 'hone in on a specific spot'.

It is believed they have a good idea of where the noise was coming from, but council chiefs say they will remain tight-lipped about the source.

John Boyle, the council's director of community and wellbeing at the council, told his colleagues that 'unless there are formal, public legal proceedings, we would not be naming the source of that noise', The Times reports.

Boyle reported the findings to the regeneration and community committee, in which he revealed how the experts went about trying to trace the source.

He wrote: 'A calibrated recording of the hum' was made using a sound level meter within a complainant's home and shared with the noise consultant who identified 'a significant dominant acoustic tone considered to be an indicative component of the hum ... This distinct tone was likely to be associated with the operation of a fan or ventilation-type equipment.'

The report added: 'Once in receipt of this information, the department was able to undertake a more targeted screening exercise on a number of industrial businesses known to use such equipment and operate on a 24-hour basis.'

A statement from the council suggests while investigators have a good idea of where the hum came from 'no conclusive evidence' has been obtained.

In a message drafted in June, the council said: 'A thorough and detailed investigation to identify the noise source was undertaken, which included the Environmental Health Service working with a specialist noise consultant.

'A particular industrial premises was identified following a targeted screening exercise, however, when further noise monitoring was carried out at the premises, no conclusive evidence was obtained to match the specific noise tone identified from previous recordings.'

Since the investigation, the council said complaints about the hum have dropped off and it is 'no longer audible.'

It added however that the noise complaint will remain open should it return with a vengeance.

The source of the hum has fascinated people far outside of Omagh.

In August, the BBC aired a special documentary featuring local journalist Emmet McElhatton and local repairman Jamie Ryan, who started his own investigation into the elusive sound, as they attempted to solve the mystery.

Omagh's hum is also not the first time a persistent buzzing has kept people awake at night.

In June, MailOnline reported that Aussies have been complaining about a mysterious rumbling sound that lasts 'all night long' in North Sydney .

Residents in Crows Nest and St Leonards vented their frustrations about the 'constant' and 'repetitive' hum that many claim has been appearing on and off for years.

The noise switches from a rumbling hum to a more 'electronic warble' that many have dubbed 'alien-like' and 'all consuming'.

Several offered suggestions as to what the odd hum could be and questioned if it's noise from trains, water pumps, extraction fans, planes or construction.

Conspiracy theorists, however, had a 'clear' answer: aliens.

Others who claimed to have heard the noise said they feel like they're 'going mad'.

Elsewhere, for decades scientists have been baffled by the phenomenon known as the Bristol Hum - where thousands of people around the world have reported hearing indistinguishable sounds emanating from the sky.

The mystery even featured on an episode of the hit US TV show, The X-files, in 1998.

The first investigation into the Phenomenon was carried out in 1973 and examined 50 residents living in the UK city of Bristol that claimed to be hearing a 'low throbbing background noise' - often early in the morning.

Since then thousands of people across the globe have also experienced the strange sound - in the American state of New Mexico it's referred to as the Taos Hum and in Canada's Ontario locals know it as the Windsor Hum.

Over the years, conspiracy theorists have blamed the noise on secret military experiments, alien spacecraft and a host of other paranormal explanations.