Marc Lallanilla
Live Science
It creeps in slowly in the dark of night, and once inside, it almost never goes away.
It’s known as the Hum, a steady, droning sound that’s heard in places as disparate as Taos, N.M.; Bristol, England; and Largs, Scotland.
But what causes the Hum, and why it only affects a small percentage of the population in certain areas, remain a mystery, despite a number of scientific investigations.