The BBC News reports on the strange low-frequency "hums" that have annoyed people and fueled conspiracy theorists around the world for years. Perhaps the best-known example in the United States is called the Taos Hum because many people in Taos, New Mexico claim to hear it. In the UK, there's also the Bristol Hum and the Largs Hum. Audiologist Dr. David Baguley and researchers from the University of Salford are studying the problem to help those who suffer distress because of the weird hums. According to Baguley, "In about a third of cases there is some environmental source that can be tracked down and dealt with... Most of the time, however, there is no external noise that can be recorded or identified." From the BBC News:
His own theory - based on years of research - is that many sufferers' hearing has become over-sensitive."Have you heard 'the Hum'?"
Surrounded in his office by plastic models of human ears, he explains how we each have an internal volume control that helps us amplify quiet sounds in times of threat, danger or intense concentration.
"If you're sitting by a table waiting for exam results and the phone rings you jump out of your skin. Waiting for a teenager to come home from a party - the key in the door sounds really loud. Your internal gain is sensitised."
This is a mechanism we all rely on at moments of pressure or stress when we want our senses on full alert.
According to Dr Baguley, the problem comes when an individual fixes on a possibly innocuous background sound, and this act of concentration then triggers the body's "internal gain", boosting the volume.
The initial "signal" may vary from person to person, but the outcome is the same.
"It becomes a vicious cycle," he explains. "The more people focus on the noise, the more anxious and fearful they get, the more the body responds by amplifying the sound, and that causes even more upset and distress."