sept 11th was my second day of work in the "real air force" as an F-16 Crew Chief thats why i remember it was a tuesday..

(Basic>Techschool>FTAC at first duty station>Real Air Force)

we were night flying, so i was asleep when my buddy that was a week behind me in FTAC said i needed to go to the day room and turn on the TV, "i told him that he had better tell me what the hell is going on to make me get out of bed" so he told me

i got up, watched TV for a few minutes, figured i should probably report into the squadron, so i walked over in my civvies to let them know i was live and well (single dorm life yo!), had to ask for permission to walk back to my dorm to get my uniform, and proceeded to help out the best i could without a line badge (second day, they hadnt gotten the paperwork completed), was really NOT the day to be missing that particular credential.. so i rode around in the breadvan and popped out to help wherever i could.. then a crop duster managed to send the entire base running inside for cover because he did not file his flight plan that day, and instead of.. oh, i dunno, incepting him and forcing him to land..

anyways, FAA regulations state that there are VERY few places where an aircraft can break the sound barrier, i know you said "sonic speeds" (and not super sonic) i also realize that in certain exceptions can be made, but additionally, low altitude sound barrier smashing is incredibly inefficient for fuel, so its not really a thing, also there is such a thing as "overspeeding" an aircraft.. odds are you heard the afterburner, its a lot louder than people give it credit