Overview
For decades, reports of a low, persistent droning known simply as “The Hum” have circulated from Bristol and Taos to parts of Canada, Australia, New Zealand, South Africa, and Europe. The sound has often been described less as a clear tone than as a vibration or diesel-like rumble, and in some cases it has been intense enough to disrupt sleep and daily life. A new study from the Norwegian University of Science and Technology (NTNU), published in PLOS ONE, suggests that for many people the explanation may not be found in the environment at all, but within the listener’s own auditory system.
What the Norwegian study found
Researchers behind the NTNU work say their findings point to tinnitus—the perception of sound without an external source—as a likely contributor to many Hum reports. That does not necessarily mean every account is the same, or that no external noises are ever involved, but it does challenge the longstanding assumption that a single, mysterious signal is traveling through neighborhoods or cities. Over the years, proposed causes have ranged from industrial ventilation systems and military sonar to ocean-generated infrasound and, in some online circles, even extraterrestrial signals. The new study, however, adds weight to the idea that at least some of these cases may be rooted in internal hearing phenomena rather than outside transmission.
The Hum first drew wider public attention in Bristol, England, in the mid-1970s, when residents reported a strange low-frequency sound that persisted even after one suspected industrial source shut down. A similar wave of complaints emerged in Taos, New Mexico, during the 1990s, prompting investigations by state and federal authorities that ultimately failed to identify a definitive source. Those cases helped cement The Hum as one of the most widely discussed acoustic mysteries of the past half-century, especially because the reports often came from otherwise ordinary settings where no obvious machinery or infrastructure could explain the noise.
A separate mystery beneath Utah
In a separate but related example of unexplained low-frequency rumbling, researchers at the University of Utah say a deep seismic mystery beneath the state may be tied to highly anomalous deep earthquakes linked to mantle stress near the Wyoming Craton. While not the same phenomenon as The Hum, the Utah case underscores how difficult it can be to distinguish human perception, surface noise, and deep geophysical activity. Scientists involved in that research suggest the rumbling is likely rooted in unusual tectonic behavior far below the surface, offering a natural explanation for what has otherwise seemed like a baffling acoustic event.
Why the findings matter
Taken together, the Norwegian and Utah studies show that reports of mysterious sounds do not necessarily point to a single grand explanation. In some cases, the answer may lie in physiology, especially if tinnitus is shaping what people hear; in others, the source may be deep Earth processes that are still poorly understood. For researchers, the challenge is not only identifying a sound’s origin, but also determining whether a reported hum is being generated outside the body, within the ear, or from geologic activity that only appears mysterious from the surface.
