"The Hum" bedevils tiny English town

It's enough to drive a man mad. It's only audible at night, apparently, and only distantly so - faint enough that the source remains indeterminable, but loud enough to be certain it's not one's imagination. It's been heard elsewhere, too, and speculations abound as to the cause. And it's been bothering residents of the English village of Woodland for at least two months. From Time:

Known as "the hum," the freaky noise hits the town of Woodland in County Durham every night. And, no, this isn't some lousy B-list horror flick plotline (although, it very well may turn into one).

Every night for the past two months the noise resembling the hum of a car engine has seemingly moved through the air, flooding the entire town's population of 300 with the annoyingly undetectable sound. Sometimes it gets so strong it shakes beds. Sometimes it grows louder in different parts of the same home. But no matter how loud, it's entirely a mystery.

Apparently, this isn't this isn't the first time "the hum" has troubled an English town. And similar phenomena have occurred elsewhere in the world, too. Wikipedia explains that

Hums have been reported in various geographical locations. In some cases a source has been located. A Hum on the Big Island of Hawaii, typically related to volcanic action, is heard in locations dozens of miles apart. The local Hawaiians also say the Hum is most often heard by men. The Hum is most often described as sounding somewhat like a distant idling diesel engine. Typically, the Hum is difficult to detect with microphones, and its source and nature are hard to localize.

The Hum is sometimes prefixed with the name of a locality where the problem has been particularly publicized: e.g., the "Bristol Hum", the "Taos Hum" or the "Bondi Hum".^[1]

You can read more here and here.