Found this thread by Google searching "loud boom Kentucky". I got off the phone with my aunt a few hours ago and she told me that a week ago she heard two booms while in bed, sometime after midnight. A friend of hers that lives near heard them, too. Another friend of hers reported the booms so loud it shook her house and that she heard a roar in the sky beforehand. Well, another news article that popped up was this one from 2009:
Loud Boom Rocks Southern Kentucky
27 NEWSFIRST started receiving phone calls tonight telling us a loud boom, or series of booms were heard this evening in Southern Kentucky.
So we called emergency officals, to find out what is going on.
Brian Reams of the Laurel county EMS tells us they've had calls from Jackson to London, about a loud boom.
He says there are no reports of any injuries or damage.
In the last little bit, Reams says he's been told by the state police in London that according to the FAA, the boom is from falling debris, coming from two satellites that collided in space.
The debris re-entering the atmosphere caused the loud boom, and then burned up before hitting earth.
Reams says it could have covered a 500 mile area.http://www.wkyt.com/home/headlines/39600267.html
There is also a lot of articles covering noises in our atmosphere that scientists are saying could have explainable causes, but that's not really a field I am knowledgeable enough about to discuss. Just adding another possibility.