Well, I followed the advice of leaving a note. It said something very close to the following:
"Hi Neighbors (there are two dudes who share the apartment - at least to my knowledge),
Could you please make sure to keep it down between 10PM and 6AM. Last night was not the first time that I was awakened by noises coming from the bedroom below mine. Thanks!"
I thought that was nice and got the point across. I didn't think it required any response on the part of the neighbor. I certainly didn't think that it would elicit a visit from the neighbor's big-mouthed girlfriend. Oh yes, she came on upstairs to tell me that it wasn't them making noise because her boyfriend works 1st shift now and they were in bed at 10:30. She then tried to blame the noise on other neighbors. I said to her, I hope politely, that I was fairly certain that the noises were not the noises of loud TVs and/or children (the only other noises in my apartment building, and which do not disturb me because of the layout of the building) and that the noises that awakened me happened at 12:15 AM and that they sounded like they came from people who had gone to bed. I then thanked her for coming up and said goodbye.
1) If you weren't the one making the noise, why not just ignore my note?
2) Why would you, the girlfriend, address the note when to my knowledge you are not a permanent resident of the apartment below?
My suspicion is that she addressed it thinking that it would stop me from ever complaining to the landlord. What she in her utter stupidity does not realize is that it actually encourages me to do so, because I suspect that she's living there and isn't on the lease. Yes, I realize I'm being kind of an asshole (or at least thinking about it), but I was really appalled that she had the audacity to confront me and to lie about the noise. I recognized her voice from the sounds that come through the floor.
I should note, however, that I had a blissfully uninterrupted night's sleep last night. Oh yes I did.
3 years ago