So the situation is that I have a neighbor in an apartment building who plays very loud music, well into the night. I have sent this neighbor a letter asking (in a calm and polite tone) to please turn down their music after 10:00 pm. I included a printout of the city noise ordinance as well. I also let building management know I was having this issue. Long story short, the quiet lasted about a week and now is back to full blast.

My question is, what other steps can I take? I have sent a letter, and contacted the building management, who this person appears to have ignored also. I'd rather not call the police about this but is that the obvious next step?