The phenomenon known simply as "The Hum" first entered public awareness in the 1970s, when residents of Bristol, England began complaining about a steady, low-frequency sound hovering around 50 Hertz that seemed to have no identifiable source. In the decades since, similar reports have emerged from Australia, New Zealand, and multiple locations across North America. Those who hear it describe it as a hum, a drone, or a rumbling that can be maddeningly persistent — and often, no one else around them can hear it at all.
Researchers led by auditory scientist Bonifaz Baumann of the German Center for Vertigo and Balance Disorders (DSGZ) decided to approach the mystery from a different angle. Instead of hunting for an external sound source — which previous investigations had failed to find — they studied the people who hear The Hum themselves. The team recruited 28 volunteers through a social media campaign and tested two leading theories: that these individuals have unusually sensitive low-frequency hearing, or that they are perceiving sounds produced inside their own ears, known as otoacoustic emissions.
The results, published in PLOS One, ruled out both explanations. Standard hearing tests showed that most participants had average low-frequency sensitivity — only two of the 28 had exceptional hearing. Measurements of otoacoustic emissions, the tiny sounds produced by the hair cells in the cochlea, also showed nothing unusual. This led the researchers to a third explanation: low-frequency tinnitus. Tinnitus is commonly associated with a high-pitched ringing in the ears, but it can also manifest at lower frequencies. The team concluded that for many people who report The Hum, the sound is a subjective auditory experience generated within the brain's auditory pathway, not an external noise that needs to be tracked down.
Neuroscientist Markus Drexl of DSGZ and the Norwegian University of Science and Technology explained that while the study does not rule out cases where a real external sound source exists, the evidence points toward low-frequency tinnitus as the most plausible explanation for a significant portion of reports. The finding is important because it reframes the experience: tinnitus is a real neurological phenomenon, not imagination. People who hear The Hum are not mistaken — their brains are genuinely processing a sound that does not exist in the outside world. The study opens the door to potential treatments for those who find the experience distressing, using approaches already developed for conventional tinnitus.
Knowledge takeaway: German researchers tested 28 people who hear The Hum and found that neither exceptional hearing sensitivity nor inner-ear sounds explain the phenomenon; the most likely cause is low-frequency tinnitus, a form of subjective tinnitus that is less recognized than the high-pitched version; the study was published in PLOS One and suggests that treatment approaches used for conventional tinnitus may help those distressed by The Hum.