The mysterious hum heard around the world may finally have an explanation | ScienceDaily

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The mysterious hum heard around the world may finally have an explanation

The mysterious worldwide Hum may often come not from distant machines, but from within the auditory system itself.

Date:<br>July 19, 2026<br>Source:<br>Norwegian University of Science and Technology<br>Summary:<br>The mysterious sound known as The Hum has been reported worldwide for decades, yet its source often remains impossible to find. Researchers tested whether people who hear it have exceptional low-frequency hearing or measurable sounds produced inside their ears, but neither explanation fit most participants. The strongest possibility is that many cases involve low-frequency tinnitus, even though the sound seems completely external.<br>Share:

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Theories about the cause of the phenomenon The Hum abound, from acoustic pollution originating from human sources, to sounds that nature itself makes. Or that the ear itself produces the humming sound. Credit: Idun Haugan, NTNU

Do you sometimes notice a deep buzzing or humming noise that seems to have no identifiable source? If so, you may be among the estimated 2-4 percent of people worldwide who experience this unusual sound. Researchers have spent decades trying to determine where it originates.

For some, the noise is irritating but manageable. For others, the low-frequency sound can cause physical discomfort or illness and may also feel like a vibration moving through the body.

The hum can be difficult to detect outdoors. It is more commonly noticed inside buildings, especially at night when people are trying to sleep. Someone may look outside for a nearby engine or machine, only to find nothing that could explain the noise.

Even more puzzling, other people in the same room may hear nothing at all.

Reports of The Hum Begin in England

The phenomenon first gained widespread attention in Bristol, England, during the mid-1970s. The Bristol Evening Post began receiving a stream of letters from residents who described hearing an unexplained sound and wanted to know what was producing it.

One proposed explanation pointed to large industrial fans operating inside a department store warehouse. Yet the reports continued even after the warehouse closed several years later.

Similar accounts later emerged elsewhere in the United Kingdom, particularly in coastal communities including Hythe, Plymouth, Southampton and Swansea. Reports also came from London.

The mysterious sound became known as The Hum phenomenon, or simply The Hum.

During the 1990s, reports began appearing in the United States, initially in Taos, New Mexico and Kokomo, Indiana. The phenomenon has since been documented in Canada, Australia, New Zealand, South Africa and several European cities. Most reports tend to come from relatively densely populated areas.

According to the Norwegian Broadcasting Corporation (NRK), residents around Oslo also reported an unexplained humming noise a couple of years ago.

Canadian teacher Glen MacPherson first heard The Hum while living and working on the west coast of Canada. After moving to another city in the same region, he could no longer hear it.

His curiosity eventually led him to establish the interactive The World Hum Map and Database Project in 2012. The project gathers reports and location data from people who say they have experienced the sound.

Possible Sources Range From Machines to Nature

Researchers and the public have proposed numerous explanations for The Hum. Suggested causes include acoustic pollution from human activity, naturally occurring environmental sounds and conspiracy theories involving the CIA or even aliens.

Many technologies can generate low-frequency noise, including ventilation systems, heat pumps, road traffic and windmills. Nature also produces sounds in this range through sources such as ocean waves striking the shore and wind moving across the landscape.

The mystery has drawn the attention of hearing specialists and audiology researchers around the world. One of them is Markus Drexl, a professor at the Norwegian University of Science and Technology (NTNU).

Drexl, two PhD research fellows and a postdoc studied 28 people in Germany who reported hearing an unexplained hum or buzz.

Testing Whether the Hum Comes From Outside

The researchers examined two main hypotheses.

The first was that The Hum might be an externally produced sound that could be measured. Such noise could come from industry, infrastructure or natural processes that generate low-frequency waves.

"We know that there are people who hear low-frequency sounds that can actually be measured, even if other people don't hear them. But it's not so easy to find the source of these sound waves, because it's a struggle to localize low-frequency sounds," Drexl said.

Low-frequency sound waves have long wavelengths, which...