Not to argue with you, but honestly, what would the cops do? The most they can do is make them be quiet, and hopefully you've already called them and they've done that.
First, make sure they are breaking the law (for example, most ordinances have times on them, so it would have to be, say, loud music after 10 p.m.). Once you are sure they are breaking the ordinance instead of just annoying you, make sure you file police reports and keep copies of them. If your complaints don't result in a change of the neighbor's behavior, then you can file a complaint against the police department.