I've heard it, but I just assumed it was coming from a mine nearby, but the droning continued for months, so I asked Toy to listen, she couldn't hear it.
The only place you could hear it was in the back 2nd floor bathroom, but when I'd go outside, you can't hear it, until you put your ear to one particular support that's mounted on solid rock, that's when my Brother really heard it.

QuoteJust this very moment I took Toy out to the post and she finally heard it.
It's been going on for years steady, so I know it's not equipment, or a generator, most likely the earth talking.

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. [The Top 10 Unexplained Phenomena]

Reports started trickling in during the 1950s from people who had never heard anything unusual before; suddenly, they were bedeviled by an annoying, low-frequency humming, throbbing or rumbling sound.

The cases seem to have several factors in common: Generally, the Hum is only heard indoors, and it's louder at night than during the day. It's also more common in rural or suburban environments; reports of a hum are rare in urban areas, probably because of the steady background noise in crowded cities.

http://www.nbcnews.com/science/mysterious-hum-driving-people-crazy-around-world-6C10760872

This is the oddest thing I've have ever heard. I also heard that it is happening in other countries as well. I wonder what is going on with these areas. Maybe Aliens?