Keep a log of each disturbance
Note when excessive noise occurred, what type of noise it was, and any actions taken on your part. This will be helpful to your management office if there’s a safety concern and/or it’s a recurring issue.
“Monday, September 12: Noisy party going on from 11 pm-1 am. Footsteps, music, loud socializing. Slipped a note under the door asking them to keep it down but no effect.”
“Saturday, June 2: Loud arguing around 3:45 am, female and male voices shouting over each other along with crashing sounds (like broken dishware?). Have not addressed the situation.”
Ask other neighbors
If others near your unit have heard loud disturbances, it may bolster your claim when you approach the building or community manager.
“Hey, I live in #402, I’m just curious if you’ve also heard excessive noise coming from #502 at odd hours?”
“Hey, I live downstairs from you and was wondering if you could hear that loud party going on next door to you until 3?”
Approach your landlord
Show your landlord your log of noises and ask what they can do about it (e.g., send an anonymous noise complaint, talk to the neighbor, or mediate a conversation between the two of you).
“Hey, I’ve been hearing a lot from my upstairs neighbor at odd hours. As you can see from this log, they seem to like late noisy parties on weekdays. I’ve slipped notes under the door but nothing has changed in the past few weeks. Do you think you could talk to them about keeping it down during weeknights?”
“I’m a bit concerned about the noises I’ve been hearing from my upstairs neighbors. A couple seems to be fighting very loudly and late at night. Here’s a log of all the noises I’ve heard. Could you address the situation?”