I was at a friend's house while he was gone and I took advantage of the time alone. The hallway isn't that big but there was a lot of activity around and the thrill of a new unknown place did it for me. People talking, taking the trash, cars stopping, etc. I had the feeling (as I did before on similar occasions) that a neighbor heard someone's outside and looked through the peephole, because I once heard him talk right next to his door but he didn't get out. So....I'll never know but who knows.