<human>: Just now, some woman from 3 floors down came up to my apartment. She asked if there were problems going on here in the mornings. Naturally, I was ridiculously confused. She said there is some kind of banging sound, as if someone is dropping dumbells, or a safe(o_o), at around 7:00AM every morning, which lasts for an hour or more. All of the apartments along the same line, up to hers, can hear it, and complain, according to her. I assured her that everyone either left for work or school, and that I would know if there was this intense noise going on that she, being 3 floors down, could hear. 

She had an extreme attitude, and I could tell by her tone and the way she was looking at me that she thought I was lying to her. She said that whatever it was needed to stop, or the police would get involved. Again, it was like talking to a wall. I told her it was impossible, even IF someone were dropping a dumbbell on the floor, that she, 3 huge floors down, could hear it. I told her to take it up with the super, because it could be the pipes or something. At this point, she said that she had studied sound waves in college and that she was certain it wasn't pipes, but the vibrations in the building from someone in our apartment dropping something. I know nothing will happen with the police, but I am very curious as to what the sound is, because it is 100% not from my apartment. I really want her to feel like a moron for so adamantly accusing me for the noise. 

So, what could it be?

Give me the gist of the text in a nutshell
<bot>: Neighbor from **3 floors down** can hear some banging, thinks I'm throwing a safe/weights at the floor every morning at 7.