The Hum: The Sound Only 2% of People Can Hear
It usually starts at night. A low, pulsing drone, like a diesel engine idling somewhere just out of sight. The listener walks through the house, unplugs appliances, checks the street — nothing. Earplugs don't block it. Moving to another room doesn't help. And when they ask family or neighbors, they get the same unsettling reply: I don't hear anything.
This is the Hum, a phenomenon documented on several continents for half a century. The first famous outbreak came from Bristol, England, in the 1970s, when hundreds of residents complained of a maddening low drone; local investigations pointed to traffic and industry but never settled the matter. In the early 1990s the small town of Taos, New Mexico, gave the phenomenon its popular name. After residents petitioned Congress, a team of scientists from Sandia and Los Alamos national laboratories and the University of New Mexico swept the area with sensitive equipment tuned to the lowest audible frequencies. They found no external source at all — yet roughly 2 percent of surveyed residents insisted the sound was real, a figure that echoes across Hum studies worldwide.
The reports are strikingly consistent. Hearers typically describe a rumble in the range of roughly 30 to 80 hertz, stronger indoors than outside, worse at night, and impossible to escape. Many are middle-aged or older. For some, the Hum is a nuisance; for others it brings insomnia, headaches, and real despair.
Sometimes there is an answer. In Windsor, Ontario, years of complaints and diplomatic pressure eventually pointed across the Detroit River to blast furnace operations at the Zug Island industrial complex on the American side — and when steelmaking there wound down in 2020, the Windsor Hum largely faded. In Kokomo, Indiana, investigators traced complaints to industrial fans and a compressor at local plants. But these local victories only deepen the puzzle: in Taos, Bristol, Auckland and dozens of other locations, no machine has ever been found.
That failure has pushed researchers toward the ear itself. One line of evidence suggests that for many hearers the Hum may be generated internally — a rare form of tinnitus, spontaneous activity in the auditory system, or a brain that has learned to amplify faint low-frequency signals. Geoscientist David Deming, himself a hearer, surveyed the evidence in 2004 and argued the phenomenon deserved serious study; teacher Glen MacPherson's World Hum Map has since gathered thousands of reports from around the globe.
What remains unanswered today is the core question: is the Hum one phenomenon or many wearing the same name? Some cases are clearly industrial noise, some may be internal, and a stubborn remainder fits neither explanation. Half a century on, no theory covers them all — and somewhere tonight, someone is lying awake, listening to a sound no one else can hear.