If you have tinnitus, then you probably have some idea of what it must be like to hear a constant, inexplicable sound that no one else hears. That’s what people all over the world have been experiencing when, for years, they’ve been hearing a mysterious low-frequency hum. Surely, it must’ve been coming from some kind of physical source? New research suggests that it might actually have been coming from their own heads this entire time, and it might have been the inverse of tinnitus.
According to a study published in PLOS ONE, researchers tested 28 people in Germany who reported hearing the so-called “Hum,” a constant low-frequency droning people describe as rumbling or throbbing. It’s been reported in people all across the world, from England to Mexico to Canada to the United States to Australia. People who suffer from it blame all sorts of industrialized menaces, like factories or piping. Some have even gone as far as to blame it all on a vast government conspiracy.
But when a team of scientists led by Markus Drexl of the Norwegian University of Science and Technology dug into whether there were any real-world sources of the hum, the explanations just weren’t there, and it all increasingly started to look like it was a phenomenon existing inside the heads of those suffering from it.
The Mysterious Humming Was Inside Their Heads All Along
First, the team looked into whether the hum hearers had unusually sensitive low-frequency hearing. Maybe if they had some kind of superpowered ability to hear stuff, then maybe they were detecting environmental sounds most of us can’t pick up. Most of them didn’t have sensitive hearing. Their hearing thresholds were hovering around normal levels, with only a few participants showing any increased activity in their hearing ability.
With that ruled out, the researchers moved on to whether the inner ear itself might be generating a low-frequency sound that only the participants could hear. Again, they didn’t find much. Sure, the cochlea can emit faint tones, but none were in the low 50-hertz range most participants reported.
All that was left was to dig a little deeper into the head, which led the team to an internal explanation for all: low-frequency tinnitus. Tinnitus is usually a high-pitched ringing sound experienced by people who’ve spent a lot of time in noisy environments without proper sound-dampening earbuds/headphones. This version is its opposite, instead producing a deep, steady hum.
Nearly 39 percent of participants also reported the typical high-pitched tinnitus, but 68 percent said the hum had no clear direction. Combined, this provides clues that point to the source being inside a person’s head rather than the hum coming from some external source.
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