From everything that I've read about this phenomenon, it only effects 2% of the population. For years, it's driven me nuts and I've asked folks, "Do you hear that?" So, I can vaguely identify what some autistic people must experience - they hear things that "normal" people do not.
I've always heard background noise as far back as I can remember, and the incessant hum began around 2009. This was approximately when frack mining began, in earnest, in my region. I have no idea whether this can be associated with frack-mining, but "The Hum" occurs throughout the world. And, I experience tremors along with the humming, on occasion. Sometimes, they're so pronounced that my son feels them, as well. But, he never hears the rumbling that I do, or the deep low-frequency "booms," either.
To know that other people experience this is somewhat comforting. It would be interesting to get a head count of how many CZ members experience this, as well.
As a strict aside, my son has suggested that I might be an indigo child, whatever THAT means. Perhaps, this is something associated with whatever that is. Dunno.