How the Hum Works

By: Dave Roos  | 
Taos, New Mexico
A sign welcomes motorists to Taos, New Mexico, home of the Taos Hum.
Robert Alexander/Getty Image

It starts every night around 10 p.m., just when you're about to fall asleep. The sound is hard to describe, a persistent low rumble like an 18-wheeler idling outside your window. But when you pull the curtain, there's nothing there.

Your neighbors don't hear a thing — and the doctor has ruled out tinnitus. But here you are, night after sleepless night. The more you try to ignore it, the louder it seems to get. All around the world, people are terrorized by a mysterious incessant noise — from the Taos Hum to the Bristol Hum.


The Hum Is a Low Frequency Sound

Hum sufferers describe a low-frequency buzz accompanied by a rumbling vibration. It's worse at night, making it almost impossible to sleep. Other physical symptoms include debilitating headaches, nausea, nosebleeds and diarrhea. In one tragic case in England, the Hum has been linked to suicide.

The Hum has baffled researchers since the 1970s, when the first widespread reports of the unexplained acoustic phenomenon cropped up in rural England. Armed with highly sensitive instruments, teams of scientists have attempted to hunt down the source of the unrelenting noise. The results? Inconclusive.


Theories abound to explain the origins of the Hum, from the plausible — power lines, cell phone towers and industrial fans — to the more, uh, imaginative. Conspiracy theorists have claimed the Hum is the work of the CIA, the military, and of course, aliens.

So what exactly is this mystifying noise, unheard by most, but an absolute torture to some? Does the Hum have an environmental origin or is it, in fact, all in their heads?


Low Frequency Sounds Around the World

Bristol, England, site of the first hum
Bristol, England is the site of the first hum to be linked to a city; it's called the Bristol Hum.
Matt Cardy/Getty Images

The earliest widespread reports of something resembling the Hum originated in England in the 1970s when pockets of concerned citizens across Britain reported hearing a mysterious humming, droning and buzzing sound.

The "Bristol Hum" was the first outbreak to be linked to a specific city, in this case the southern English town of Bristol. In the 1970s, a series of articles about the Hum in the U.K. newspaper the "Sunday Mirror" triggered a flood of mail from readers across Britain who had been suffering from the same maddening sound.


News of the Hum made enough noise — pun absolutely intended — to attract the first serious researchers. In a 1977 volume of the scientific journal "Applied Acoustics," two researchers explored a "particular environmental noise phenomenon which appears to be a cause of real and severe disturbance to certain people." Their best guess was low-frequency sound waves generated by distant industrial sources.

Another famous hum began plaguing the residents of the coastal Scottish town of Largs in the late 1980s. It was the same low-pitched drone, inaudible to most, but debilitating to a sensitive few. The "Largs Hum," like other hums, is loudest indoors and at night and can trigger nosebleeds, crippling headaches and chest pains in the worst cases.


The New Mexico Taos Hum

In the U.S., the first large-scale outbreak of the Hum occurred in Taos, an artist's enclave in New Mexico. In the early 1990s, distressed Taos residents complained to their local and state representatives, eventually prompting an official Congressional investigation.

Joe Mullins, mechanical engineering professor emeritus of the University of New Mexico, led a team of acoustic researchers and hearing scientists from nearby Los Alamos National Laboratory and Sandia National Laboratories to hunt down the source of the Hum. The research team's results were inconclusive — people were clearly suffering from the same tormenting sound, but investigators had no idea where it was coming from, and why it only affected 2 percent of the population.


Sources of the Hum

We live in a world saturated by noise. From the drone of passing traffic to the incessant "dinging" of our smartphones, we are surrounded by acoustic pollution. When researchers were dispatched to Taos, New Mexico, they tuned their specialized equipment to the lowest audible frequencies, between 8 and 80 Hz. These are the ultra-bass frequencies that register more as a rumble and a throb than a perceptible tone. However, investigators were unable to isolate a single environmental source that emitted tones at that frequency.

Researchers in Windsor, Ontario, isolated a local hum to the blast furnace of a steel plant on Zug Island in nearby Michigan. However, local industrial sources don't explain the worldwide prevalence of the Hum. What else could produce such powerful and pervasive low-frequency tones?


What about long-distance radio transmissions? There's a network of radio transmitters called LORAN (long range radio navigation) that broadcasts low-frequency signals as a form of primitive GPS. Skeptics point out that if LORAN was the culprit, then we would have more reports of the Hum closest to LORAN towers. Also, LORAN broadcasts 24/7, but Hum sufferers mostly complain of the noise at night.

A more intriguing possibility is TACAMO aircraft, military planes that employ radio frequencies in the lowest end of the spectrum to communicate with submerged submarines. The planes operate at night, and their movements are top secret. Hum hearers in Largs, Scotland have long believed that their particular hum originates from the local naval base. The TACAMO theory might also explain why many Hum sites are on the coast.

Conspiracy theorists have dreamed up all kinds of wild stories for the source of the Hum, including a large-scale mind-control scheme executed by the U.S. and U.K. governments. Others believe that regardless of its source, the hum is dangerous enough to drive people temporarily insane.


Our Ears Can Create Their Own Noises

Since acoustic researchers have failed to find a single measurable environmental source for this worldwide phenomenon, it's fair to ask: Is the Hum some kind of mass auditory hallucination?

Not likely, says David Deming, a geosciences professor at the University of Oklahoma who wrote a comprehensive paper on the Hum in 2004. In previous cases of mass delusion — like the witch hunts that erupted across Europe in the 15th and 16th centuries — the perpetrators had something to gain by joining the mad throngs, namely improved social status. But the people who claim to hear the Hum have nothing to gain; some have even abandoned homes in a desperate effort to escape the noise.


What about tinnitus? As many as one in five people suffer from some degree of tinnitus — or ringing in the ears. Maybe the Hum is literally in our heads. Again, not likely. Tinnitus sufferers generally report a persistent ringing — both day and night — that registers in the highest audible frequencies, not the absolute lowest.

Another interesting theory is that Hum sufferers may simply have exceptionally sensitive hearing in the ultra-low-frequency range of 20 to 100Hz. But if no acoustic instruments have been able to record the Hum, then what is it exactly that these sensitive ears are hearing?

Dr. David Baguley, head of audiology at Addenbrooke's Hospital in England, has researched the Hum for years and blames the phenomenon on sensitive brains, not ears. Our sense of hearing is greatly heightened in times of stress, Dr. Baguley explained to BBC News in 2009. The brain cranks up the volume to detect the slightest threatening sound.

In the case of the Hum, Dr. Baguley believes people hear about the phenomenon in newspapers and around town and begin to fixate on a perceived background noise. The incessant sound becomes a source of increasing frustration, disrupting sleep, and causing additional stress, which tricks the brain into turning up the volume even further. The solution, then, is to convince the brain to back down. With his own Hum patients, Dr. Baguley has found some success with simple relaxation techniques borrowed from psychology.


The Hum FAQ

What does the hum sound like?
The hum sounds different based on who you ask, but in general, most people agree that it sounds like a truck engine that’s idling in the distance. Basically, it’s a low rumbling noise.
What causes audio hum?
An audio hum comes in two types – 60Hz and 120Hz. The 60Hz hum is usually caused by subpar cable shielding or cable issues. A 120Hz hum is caused by ground loops.
What is humming music called?
Humming music is soothing to the ears. The continuous loop of high-pitched and low-pitched sounds reverberating from a sound system is called the humwhistle or the "whistle-hum."
How can I find a song by humming?
Google has all the answers. The microphone icon on the Google app can help you find out a song’s title and artist by humming or whistling into your phone’s mic. It will then search online to try to match the sound to an existing song in order to find as close an answer as possible.

Lots More Information

Author's Note: How the Hum Works

Never underestimate the power of suggestion. I, myself, am a highly suggestible individual, especially when it comes to my health. The second one of my kids sneezes or complains of a sore throat, my nose begins to tickle. Ten minutes later, there's a lump in my throat. By the end of the day, I'm standing in the bathroom with a flashlight trying to detect white dots on my tonsils. As a side effect of my acute hypochondria, my wife refuses to tell me if she's feeling sick. She knows that the very thought of illness is more contagious to me than actual germs. I'm just glad I don't live in towns like Taos or Largs. If people started complaining about a low rumbling hum at night, I can very easily see myself lying in bed, wide awake, craning my ears for a nonexistent noise. "Honey, do you hear that?"

Related Articles

  • Alexander, James. "Have you heard 'the Hum'?" BBC News. May 19, 2009 (Jan. 30, 2015)
  • American Tinnitus Association. "About Tinnitus." (Jan. 30, 2015)
  • American Tinnitus Association. "Sounds of Tinnitus." (Jan. 30, 2015)
  • Baker, Deborah. "Mysterious Low-Level Noise Destroys Peace, Serenity of Taos Residents : New Mexico: Scientists’ search for source of hum has been fruitless, though one heard sound himself. Some victims suspect a secret military project." Los Angeles Times. July 18, 1993. (Oct. 23, 2023).
  • Barton, Laura. "What's that noise?" The Guardian. Oct. 18, 2001 (Jan. 30, 2015)
  • Deming, David. "The Hum: An Anomalous Sound Heard Round the World." Journal of Scientific Exploration, Vol. 18, No. 4, 2004. (Jan. 30, 2015)
  • Keller, Jared. "A Mysterious Sound is Driving People Insane — And Nobody Knows What's Causing It." Mic. June 19, 2014. (Jan. 30, 2015)
  • Labmate Online. "The Worldwide Hum – Delusion or Reality?". Aug. 3, 2016. (Oct. 23, 2023).
  • Mullins, Joe H. and Kelly, James P. "The mystery of the Taos hum." Echoes. Vol. 5, No. 3, Autumn 1995 (Jan. 30, 2015)
  • Novak, Colin. "Summary of the Windsor Hum Study Results." Global Affairs Canada. May 23, 2014. (Oct. 23, 2023).
  • Pearson, Craig. "Report reveals Windsor Hum is real, source Zug Island." The Windsor Star. May 23, 2014 (Jan. 30, 2015)
  • Salisbury, Vanita. "Investigating the Mystery of the Taos Hum." Thrillist. June 29, 2023. (Oct. 23, 2023).
  • Vasudevan, R.N. "Experimental study of annoyance due to low frequency environmental noise." Applied Acoustics, Vol. 10, Issue 1, 1977 (Jan. 30, 2015)