A persistent humming or pulsing noise reported by a small share of people for more than five decades is often generated inside the ear itself.
The phenomenon known as the hum has puzzled those who hear it and baffled investigators since the 1970s. First widely noted in Bristol, it has since been described in coastal areas of the United Kingdom, the United States, Canada, Australia and elsewhere. Those affected perceive a steady low-frequency sound that others around them cannot detect.
A peer-reviewed study published in March 2026 examined 28 individuals in Germany who reported experiencing these low-frequency sound percepts. The median frequency they matched to their experience was 50 Hz. The work tested two leading explanations: unusually sharp sensitivity to low-frequency sounds and the possibility that people were hearing spontaneous otoacoustic emissions produced by their own inner ears.
Only two of the 28 participants showed unusually sensitive low-frequency hearing thresholds. The majority fell within the normal reference range and displayed hearing threshold patterns comparable to control groups. No spontaneous otoacoustic emissions appeared in the low-frequency range among those who reported the hum.
Based on our results, while cases of hearing physical external sound sources are not ruled out, we suggest that subjective tinnitus in the low-frequency range is often the reason behind hearing these LFSPs.
That conclusion comes from the paper's authors, including Markus Drexl, professor at the Norwegian University of Science and Technology. The researchers stress that a single mechanism does not explain every case.
It appears that LFSPs cannot be explained by a single mechanism, but may be the result of sources that vary from individual to individual.
The findings give weight to the idea that subjective low-frequency tinnitus originating within the auditory system accounts for the perception in most individuals. External physical sound sources cannot be ruled out entirely, yet the data shift attention away from environmental culprits that have eluded detection for decades.