I don't know what the law in the US says about this, but overhere you can make pretty much as much noise as you like, as long as it's not after 10 PM. Only after that time, the police will respond to your complains. The only thing you could do (if in Holland) is convince your neighbour not to play loud music at times your little one is taking a nap. If the guy has any common sense, it shouldn't be a problem, but your neighbour seems to be a real knucklehead, and so it seems you DO have a problem.
I once was in the same situation like you. I'm not going into any details here, but some very unpleasant things had to happen to make the noise stop. I hope things will work out differently for you.
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