“The Hum” Has Hit The Hebrides – But It’s Not The First Unexplained Noise To Stump Scientists

However, sometimes the origins of these noises are unknown and far from short-lived. In fact, the presence of this type of hum becomes so disruptive that it starts to seriously impact the mental health of people living nearby.

This situation is, at the time of writing, plaguing people living on the islands of the Outer Hebrides. According to a Facebook page for the “Hebridean Hum”, around 200 locals on the Isle of Lewis have reported hearing the noise since February 2025. For a long while, it was intermittent, but has apparently recently become “loud, constant, and intrusive”.

“This noise is not just a background hum from appliances – it’s a persistent, environmental tone that can be heard indoors and outdoors in multiple areas.”

Those affected by the Hum have reported disrupted sleep, impaired concentration, dizziness, headaches, and other feelings associated with distress.  

The sound has also apparently been measured at 50 Hertz by a spectrograph, which, although considered a low-frequency sound, is still audible to most people.

Residents affected by the Hum have become desperate for potential explanations, especially as they rule out more obvious ones. For instance, the Battery Point Power Station in Stornoway on the west coast, which is owned by the SSEN electricity company, has been ruled out. This is because, so the BBC explain, the power station only operates at certain times, while the Hum appears to be more or less consistent.  

For the people of Lewis, the Hebridean Hum has become something of a haunting menace, but they are far from being alone. “Hums” have now been reported in various places across the world, and in some cases, their overall causes have not been identified. As with the people of Lewis, the phenomenon is not heard by everyone (typically just a small percentage of the local population hear it), but for those who do hear it, the noise can become incredibly disruptive. In fact, one Hum became so distressing that it has been linked to some people taking their lives.

The first Hum

During the 1970s, hundreds of residents in the city of Bristol, England, complained to the council about a strange noise they were hearing at night while trying to sleep. For some people, it was a persistent irritation, but as with other cases, it caused some residents such distress that it significantly impacted their lives more broadly. At the time, the irritation was put down to industrial noises caused by nearby factories or electricity pylons; some even dismissed it as tinnitus, a condition where someone hears a sound even though there is no external sound source. But like other cases of the Hum that would be reported after this, the noise became so disruptive that it seriously impacted some people’s health.

In 1977, the Bristol Hum and letters written into British newspapers about reports of similar noises heard elsewhere in the country, sparked the first academic study into the perplexing phenomenon. The paper, written by R.N. Vasudevan and Colin G. Gordon from the Institute of Sound and Vibration Research, University of Southampton, questioned two people in Southampton who had experienced a similar noise for several years, and carried out field measurements and laboratory experiments. In their paper, they noted that:

 “There is little doubt that in a number of these cases the problem was one of either physiologically or psychologically self-generated origin, but there is equally no doubt in our minds that in some instances the problem is a real one; that is, the complaint is caused by an acoustic stimulus of low intensity.”

They concluded that the sound in question was a low-frequency “throbbing noise” that was “particularly prevalent indoors, rather than out-of doors”. It seemed to Vasudevan and Gordon that the phenomenon was unbalanced to the point that the stimulus occurred in a frequency range of 20 to 100 Hertz, which may have been generated by industrial sources in the wider local area.

Eventually, the Bristol Hum disappeared, but reports started again several decades later in 2016. As before, people started reporting a noise that was driving them to distraction. Similar hums have also been reported from other British towns and cities, including Plymouth, Hythe, Immingham, Holmfield, and the Scottish town of Largs, to name a few.

The Taos Hum

One of the most (in)famous cases of the Hum occurred in Taos, New Mexico, in 1993. The sound was so widely known that it became the subject of a week-long Congressional investigation that sought to establish the cause of the sound or even eliminate it as a product of the imagination. This investigation was a collaborative effort, involved scientists from Los Alamos National Laboratory, Sandia National Laboratories, Phillips Air Force Laboratory, and the University of New Mexico.

According to this study, the Hum was experienced by 161 of the 8,000 people surveyed (around 2 percent), and the sound was reported as either a whir, a buzz, and the typical “hum” (it should be noted that though this sound is called “The Hum”, it is a blanket term adopted by the press to cover weird low-frequency sounds). Despite their work, the researchers could not find a conclusive cause for the phenomenon aside from a general observation that, at the time, Taos had an elevated electromagnetic field connected to the town’s power lines.

What’s going on with all this noise?

Just what is causing the Hum is still up for debate. As with any modern mystery, the proposed explanations vary widely from the plausible to the truly “out there”. Some have proposed the sounds are caused by secret military tests or covert submarine signals, while others have suggested aliens are responsible or that they are the result of 5G towers designed to control our minds.

As Jordan Tannahill noted in the Guardian, “When it comes to online discourse about the Hum, the boundaries between science, conspiracy theory and New Age spiritualism are thin.” Tannahill points out that there are even forums online where the Hum has transmuted from being a problem to being part of “Mother Earth’s frequency” that can be tapped into for mind-expanding purposes.

“By resisting definitive scientific explanation and categorisation, the Hum becomes a kind of empty vessel for us to fill with our fears, desires and flights of fancy,” Tannahill added.

More mundane explanations have included the above-mentioned disruptions to localized magnetic fields, with suggestions that humans, as with pigeons, dogs, turtles, and other animals, may be sensitive to variations in these fields. It’s compelling, but we are nowhere near having any concrete evidence that they are indeed linked to the Hum.

Alternatively, in 2015, French scientists suggested the Hum might be caused by ocean waves reaching down to the ocean floor and causing slowly oscillating, very long waves. As these slower waves move back and forth over the ocean, they collide with ridges and the bumpy features of the ocean floor. The pressure from this collision generates seismic waves that cause the Earth to oscillate, producing a low-frequency hum.

Others have conjectured that vibrations released by volcanic eruptions or earthquakes may be responsible – here, the idea is that the Earth is reverberating for some time after the initial earthquake has passed.

Perhaps these natural explanations do account for some of the hums occurring in different locations, but this phenomenon may not even have a single cause. When dealing with something that is only audible to a few individuals in contexts that are often far removed from one another across distance and time, there is no way to easily identify a generalized cause, if indeed there always is one. This latter point needs to be considered regardless of how earnest those affected by the Hum are. It is possible that some cases are the result of human psychology rather than external audio sources. Despite our claims to rationality, humans can be easily influenced by social beliefs that manifest in odd ways. History is filled with examples of this kind of psychogenic illness, such as the baffling case of the dancing plague of 1518.

This is not to say that all reports of the Hum are caused by our minds, just that, when dealing with an intangible modern mystery that defies scientific consensus, it can easily become a more complex situation. Especially with the rise of social media, which allows people to share their ideas in a melting pot of claims and interpretations.

Perhaps the affected community searching for an answer to the Hebridean Hum will find an answer soon, and hopefully it will give them all some peace. If an answer is found, I expect it will be disappointingly mundane for some spectators. Or perhaps this will be another case where the strange, irritating noise disappears as inexplicably as it arrived, leaving everyone none the wiser as to where it came from in the first place.