The Hum

In the early 1970s, humans around the globe began reporting a persistent, low frequency (30-80 Hz) noise and dubbed it “The Hum”. While there are countless reporters of the Hum, surveys indicate that only approximately 2-4 percent of humans hear it (Roos, 2023). The phenomenon has produced a multitude of theories on its origin, from industry, wind, marine life, the Earth, the military, the Central Intelligence Agency, paranormal or extraterrestrial sources (many movies, shows and social media accounts exist for this!), and maybe internal physiological factors such as tinnitus or spontaneous otoacoustic emissions (SOAEs). It is a mystery that has been investigated by scientists for decades, but the source of the Hum remains unconfirmed.  

Researchers at the Norwegian University of Science and Technology (NTNU) recently began to study the humans who hear the Hum. Thirty-eight adult subjects reporting low frequency sound percepts (LFSPs) underwent several tests and surveys. Their results were then compared to a control group who had never experienced the Hum. Studying those who perceive the Hum has proven to be simpler than studying the Hum itself, as it is difficult to localize low frequency sounds due to their long wavelengths, which allow them to travel great distances and “bend” around obstacles. The researchers first explored the most obvious possibility: people who hear the Hum have unusually sensitive hearing in the low frequencies. However, the results were not supportive of that theory, as only two demonstrated better-than-average sensitivity at low frequencies. They then proceeded with the theory that the Hum may have its origins in SOAEs, as these can sometimes be perceived by an individual. However, no SOAEs with frequencies < 900 Hz were found in the present study, suggesting that hearing your own low-frequency SOAEs is an unlikely explanation for LFSPs.

Most people associate tinnitus with a high-pitched ringing sound, but tinnitus can take many forms. Low-frequency tinnitus may be one explanation for LFSPs in those with normal hearing thresholds, especially when no external source can be identified. This theory has also not been confirmed due to many confounding factors.

The researchers conclude that the Hum does not have a single cause. Only a small number of cases can be explained by unusually sensitive low‑frequency hearing, and low‑frequency tinnitus may explain many reported cases, but not all. In addition, SOAEs do not seem feasible as a reason. LFSPs likely arise from different sources for different individuals and may likely be a combination of factors. Non‑auditory causes remain possible. In conclusion, this mystery has yet to be solved. Perhaps more investigation into its paranormal origins is warranted!

References

Koos, D. (2015). How the Hum Works. HowStuffWorks.

Baumann, B., Voss, A., Jurado, C., & Drexl, M. (2026). On the potential sources of a low-frequency sound percept that only a few can perceive. PLOS One, 21(3), e0326818.