Imagine spending your life listening to a low humming sound that never stops and that no one else can hear.

That’s the reality for thousands of people who report hearing a sound sometimes labeled the “global hum” or the “world hum.” But what is this strange phenomenon, and why does it continue to be heard by many people to this day?

The Emergence and Spread of the Global Hum

Early reports of this phenomenon first emerged in Bristol, England in the 1970s, when newspapers began receiving letters from people claiming to hear a low, droning noise that never ceased.

People from across the United Kingdom, Europe, North America, Australia, and New Zealand soon began describing a similar experience. Reports of humming sounds also popped up in the coastal Scottish town of Largs, Scotland in the 1980s, and in Whitehall, South Yorkshire, England in 2001. 

In 1993, a woman named Catanya Salzman wrote to the Taos News with reports of hearing a hum that was destroying her life. The noise kept her from sleeping, she complained, and offered the opposite of the peaceful escape she’d hoped to find in the mountain town. 

After her letter was published, other Taos locals began coming forward with similar stories, with many saying they’d begun hearing the sound about a year prior. 

The reports caused such a stir that New Mexico Representative Bill Richardson called in a team of scientists to investigate. A group of representatives from the Air Force’s Phillips Laboratory, Los Alamos, Sandia National Laboratories, and the University of New Mexico used sophisticated technology to measure the sound, but still, it remained a complete enigma.

Tracking the Global Hum

In 2012, a website called the Worldwide Hum Project launched, allowing people from around the world to report when and where they hear the hum. 

“The classic description is that The Hum sounds like a car or truck engine idling outside your home or down the block,” the site reads. “Some people describe it as a low rumbling or droning sound. It is typically perceived as louder at night than during the day, and louder indoors than outdoors. The sound can often be masked by background noise, such as a fan or keeping the radio on.”

According to the site, many people who can detect the sound typically hear it all the time. However, it notes that some people may be picking up on sounds in their environment that others cannot hear, which means they only hear the hum in specific places or at specific times.

“We try to provide the reasoning tools for distinguishing between these two types,” the website reads. 

What Might Be Causing the Hum?

Scientists have put forth many theories as to what might be behind this strange noise. 

In 2026, Norwegian University of Science and Technology (NTNU) professor Markus Drexl helped lead a study of 28 people who hear the sound. At first, the researchers attempted to determine whether these people were simply better at hearing low frequencies than others, but the results did not support this theory. 

Then they investigated whether people hearing the sound were detecting a noise that naturally occurs in the inner ear, but found no evidence to support this idea either.

Finally, they theorized that people hearing the hum might have a unique form of tinnitus—the phenomenon that typically causes ringing in people’s ears. This was the most convincing theory, Drexl said. 

“Based on our results, although we haven’t ruled out cases of physical external sound sources, we suggest that subjective tinnitus in the low-frequency range is often the cause of hearing pulsations of low-frequency sound perceptions,” he said, per Sci Tech Daily.

Ultimately, though, the researchers concluded that there are likely multiple different reasons why people hear the hum, which would explain why some people hear it all the time while others only hear it in certain places. 

Scientists have floated numerous theories about what might be behind the hum over the years. In 2015, a group of French scientists proposed that it might be caused by the interaction of microseismic waves with seabeds. However, their research couldn’t explain why the sound sometimes comes and goes for certain people.

Some people have also blamed the sounds on gas pipelines, wind, and electromagnetic frequencies. Conspiracy theorists, meanwhile, have connected the hum to CIA activity, while others have suggested paranormal explanations such as aliens or ghosts. 

Ultimately, more research is needed to fully understand what might be causing hum. 

“What we know about the hearing system is mainly based on how we capture and process sound with higher frequencies. We know less about how the auditory system handles and processes low-frequency sound, or infrasound,” Drexl continued. “If we want to conduct a thorough assessment of low-frequency sounds and infrasound, we first need a better understanding of how sensory systems process low-frequency sound and infrasound.”

Today, the hum continues to drone through many people’s days and nights. “It sounds like an overhead power line with this constant humming buzz,” Kevin Fail, a bathroom installer living in Durham, told the BBC in 2011. Another unnamed “hearer” described it as “an endless riff of heavy metal music…difficult to say if felt or heard,” per The Guardian. 

What to Do If You Hear the Hum

The hum can sometimes be distressing for people, but the best way to deal with it is by accepting it, at least according to Dr. David Baguley, head of audiology at Addenbrooke’s Hospital. 

“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 told the BBC. “It’s a question of whether you tense up to the noise or are relaxed about it.” 

He also noted that people shouldn’t expect a clear explanation for what might be causing this phenomenon to emerge anytime soon. “It’s been a mystery for 40 years,” he said, “so it may well remain one for a lot longer.”

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