I'm sure glad you aren't my neighbor, who is looking for trouble. It isn't his business why should he bend over backwards and possibly ruin his living situation? Just make an anonymous call to the cops and report the situation. Retaliation is a foot away if he makes it apparent that it was him that called the cops. Once you take upon the situation yourself you become involved and some people just don't want to have that shit on their minds when they come home to relax. When I get home I want to be happy and calm and not be up in someone else's business. Leave it to the authorities to do your job, who needs to be some fucking hero it isn't your business especially if it isn't overt. It is extremely rude to be sticking your nose into someone else's business and apparently you don't get that. Maybe that child is just rude and the parent's may be nonviolent and just slam the door? Without understanding the totality of the circumstances what gives you the right to go in and accuse someone of wrongdoing albeit the noise may be shitty, just let them know through a note or something. No one wants drama where they want to live peacefully, all you are asking to do is start drama.