When I was around seven years old, in the middle of the night I was suddenly awoken by a thunderous, distinct and consistent banging noise. Difficult to describe, the sound and magnitude of reverberations could be compared to that of a basketball being bounced on the hardwood floor of a gym. Only this disturbance was coming from the level above me, where the floors were completely carpeted.
Being so young, I was terrified and buried myself under my covers and pillow, trying to wait it out. No such luck, it continued indefinitely. My room door suddenly swung open and a light peered through. It was my brother - shining his flashlight around whispering my name. "Do you hear that?", I hesitantly answered yes.
We briefly argued about going to see what it is, he said "we have to." I suggested waking up our parents, but knowing them during that time they would be furious and the consequences would not be worth it. I seriously did not want to go see what it was, I was bent on lying in bed and waiting it out, but my brother somehow convinced me to accompany him.
By now the thunderous noise must have been echoing continuously for at least five to ten minutes. Armed with a flashlight, wooden swords and I think an arrow (we practice archery and martial arts among other things, I wanted something sharp to brandish lol), we made our way through the dark, upstairs, which is a half floor, remodeled from the original attic. I mention this because its a small area that can't reflect or echo sounds like the ones we were hearing.
Nothing. The sounds stopped, we looked around for anything that could be related or even possibly make a remotely similar racket... Nothing.
Looking back on that incident 20 years ago its hard to remember details like if the sound caused anything to vibrate or rumble in the house, or at exactly what point the sound stopped. My brother and I still reminisce about it from time to time, and my parents are always baffled and in disbelief that they slept through something like that.