A Low Hum Has Haunted People for 50 Years

Somewhere between 2 and 4 percent of the world's population hears a low, persistent drone that sounds like an idling diesel engine. For some, it disrupts sleep and causes ongoing stress. What makes it especially strange is that many people standing in the exact same place hear absolutely nothing. Scientists have spent decades hunting the source. A new study suggests the sound may be coming from inside the listener all along.

A team of researchers from Germany and Norway tested people who experience the phenomenon directly, studying what scientists call low-frequency sound percepts, or LFSPs. They explored two hypotheses. The first: maybe people who hear The Hum simply have unusually sensitive low-frequency hearing. Results offered limited support. Most participants showed normal hearing, and only two demonstrated above-average sensitivity at certain low frequencies. The second hypothesis was that participants might be hearing spontaneous otoacoustic emissions (SOAEs), faint sounds the inner ear generates on its own as a byproduct of normal cochlear function. The researchers found no low-frequency SOAEs in either the hum-hearers or the control group; the cochlea's naturally produced sounds typically range far above the frequencies people report hearing.

The most plausible remaining explanation is that people hearing The Hum may have an unusual form of tinnitus, the phenomenon that typically causes ringing in the ears. That explanation comes with a wrinkle. The Hum was first documented in Bristol, England, in the mid-1970s, when letters poured into the local paper. One theory blamed large industrial fans in a nearby warehouse. When the warehouse closed, people continued to hear the sound.

The researchers are careful to note that external sources haven't been ruled out. The Hum does not appear to be a single phenomenon: different cases have been attributed to local mechanical sources as well as biological auditory effects. The study's honest conclusion is that no single mechanism explains all of it.

The ear generates a sound that fools the brain into thinking it's coming from outside. The outside world keeps failing to produce it.

Read the full story at Norwegian SciTech News, June 2, 2026

Hot Take: The low hum sounds uncommon until the numbers kick in. Two to four percent of people hear it, which means you already know someone who’s mentioned it and more who haven’t. Like bugs, the ones you know about don't represent the full population.