Andreas- I do apologize that you did not feel secure in the apartment. The door to the main house is always closed and locked, but you are correct, it is locked from the other side. It's one of the quirks of living in a 115 year old house, unfortunately. As for the sound, you can absolutely hear us walking around upstairs, but I can assure you that we cannot hear the people in the apartment's conversations. We're working on better soundproofing the space, but it looks like that might require ripping up the entire first floor and putting down another layer of insulation, which we can't do.