I had a sim who just got her first apartment after working hard from living on a decrepit lot (a bit of a rags to riches challenge I am working on and having fun with). First night a neighbor started making noise. But my sim was feeling up to some guitar busking so she ignored the noise and just went down to the common area to make tips.
Next night my sim takes a shower, practicing her singing in the process, and that one sim who was making a racket the night before had the nerve to complain. I ignored her and she promised that there would be consequences! OOOOOooo I'm scared. Might be time for Penny Pizzazz to find somewhere else to live. Never much liked her from the getgo.
I've had very limited success with knocking politely as most of the times such knockings aren't heard or just ignored. I find it is best to just pound on the door, complain, and see how it goes from there. If the person takes offense then the friendship hit isn't that big.
I have found that if there is a certain distance and enough walls to the offending apartment's front door, your sim will actually not be bothered by it. So if you have a decent sized apartment, I would recommend at least putting the bedroom furthest from. It'd be worth experimenting with. If there isn't enough space, then it is high time to raise enough money to get a bigger apartment, as any of the smallest apartments will be carrying other problems as well regardless. Needs TLC and Gremlins is good for if you want a Handy Sim.
It would be nice if we could null such negative traits like Noisy Neighbors, but they are there for a reason. There is a romanticism about apartment life, but there is also a cost to it. Gotta spend more to enjoy more elbow room and peace and quiet.
