Back in the day when I used to live in a multi-apartment building someone was being so loud as to wake me up in the middle of the night and I could never figure out who it was. It was an old building so the noise would transfer across many floors/walls. I was trying to come up with an engineering solution to this but in the mean time I got a new job and had to move anyway. Probably a microphone array would work to triangulate the source, but it would also be hard to explain to the police.