Do you think it could have been an earthquake? There is a minor fault line that runs through Franklin Co. on a line SW to NE I think. There was a not too serious quake there in the late 80's but I don't remember any noise altho I've read that sometimes there is.

Have you called the police or sheriff's office? Or maybe a radio station?

There have been so many reports this past year of loud booms with no logical explanation. Hope you didn't have any damages.