The deep buzzing or humming sound known as “The Hum” has been reported by an estimated 2% to 4% of people worldwide, and researchers have spent decades trying to figure out where it comes from, according to ScienceDaily.
The phenomenon has been reported in places including the United Kingdom, the United States, Canada, Australia, New Zealand, South Africa and parts of Europe. It is often noticed indoors, especially at night, and in some cases only the person hearing it can detect the sound.
Canadian teacher Glen MacPherson later created The World Hum Map and Database Project in 2012 to collect reports from people who say they have experienced it. Over time, proposed explanations have ranged from industrial noise and environmental sounds to conspiracy theories involving the CIA or aliens.
A research team led by Markus Drexl at the Norwegian University of Science and Technology studied 28 people in Germany who said they heard an unexplained hum or buzz. Their findings suggested that for many of them, the sound was not likely caused by an unusually strong ability to hear low-frequency noise.
Instead, Drexl said some cases may fit a form of low-frequency tinnitus, meaning the sound is perceived even though no external source can be measured. He also noted that very small differences in hearing could still matter in ways standard hearing tests do not capture.
