Downstairs Door

After a new neighbor moved in upstairs, I could hear the harsh creaking of the wooden door at two o'clock every night. When I couldn't bear it anymore and went up to argue, my neighbor smiled and said, "Did you hear that correctly?" "My house has no wooden doors at all. During the renovation last year, they were all replaced with security doors." I took out my phone to dig out the recording evidence, but found that every time I recorded it, there was only dead silence. The neighbor suddenly stopped smiling: "Wait a minute... Does your voice still have a damp, musty smell?" He lowered his voice and came closer to me: "That wooden door was sealed in the attic wall twenty years ago." "And..." He stared at the empty stairs behind me, "The sound was coming from the wrong direction—" "It's actually coming from behind you."