Well, if you really want to go the “tit for tat” route, I can tell you from experience (not my experience, mind you… A “friends” experience. ;)) how to really get his “panties wound up tight”. :eek:
Every time he makes an ugly comment… Smile real big, wave and say “Hey, thanks. I’m really glad to know that!” and go on your merry way. 
(Trust me, if he can’t “get a rise out of you”, it won’t take very long at all before one of two things will happen.)
The guy will either A. Think you’re a loony, and lose interest in trying to “get your goat”. or B. He’ll prove without a doubt that HE’S a loony, (and possibly a dangerous one!:() and somehow “escalate” things.:mad:
Before trying this, I would advise setting up some type of video surveillance recording, so that any further incidents or escalation can be documented.
Before I go any further, I should say… IANAL, nor do I have any “law enforcement training”. However, I do have a friend or two that are lawyers, and I know ***more than a couple ***of LEO’s… And their unanimous concensus is that your neighbor is, at the very least, “disturbing the peace” and/or exhibiting “disorderly conduct”. Your problem is that, without video documentation or eyewitness testimony from reliable and (preferrably) unassociated sources, that corroborate your version of the incident(s), it boils down to a “he said, she said… no I didn’t, yes you did”, type of situation.
But I would be willing to make a very large bet, that this man cannot legally, “use abusive, demeaning and/or insulting language in public”, and especially, if it’s directed at you, specifically! He doesn’t have to make specific threats, in order for his actions to constitute illegal behavior.
Now with all of that said, I’ve got to point out that we’ve only heard, "your side of the story".:dubious:
Like I’ve already said, IANAL. But if all you did was, “I asked him to please turn down the volume of his music outdoors.” Then you should be able to have the local LEO’s “discuss the issue”
with your neighbor. Which brings to mind, this point… Do you know ***any of your other ***neighbors? If you do, (or even if you don’t) talk to them and find out if they’ve witnessed, any of what you’ve described. (Try to get a feel as to “which camp they’re in”, first, though. It might not help matters if you inadvertently “tip you hand”, to parties that were sympathetic to him!:eek:)
All in all… I sense that you’re dealing with a very trying and exasperating situation.
You certainly have my sympathies, and I wish you luck in obtaining a peaceful outcome.
Above all though, "Hope for the best, but be prepared, for the worst!"