Hi, welcome
Although not ex police I've had some law enforcement experience.
Swearing was deamed acceptable many years ago when police somewhere in Australia charged someone and the judge threw the case out as not in keeping with modern standards of how frequently swearing is exercised in public and on TV.
Loudness is an EPA Environment Protection Authority issue. I've had dealing with them on barking dog and noise (loud music) issues. But I've never attended a noisy remises for loud voices. I'd suggest because of that rarity you wouldn't have a case.
At the end of the day you can still call police with the intention of him lowering his voice and to be asked to stop swearing. The police are likely to do that in an attempt it could make him do it all under his breath or at least quelled. The only risk is he could pin point its you that complained and hold a grudge, not a nice outcome for a direct neighbour to be in.
The alternative is to purchase wireless headphones which are remarkable in their efficiency nowadays. I bought a pair for my mobile phone and can walk around the house with them on and as they fit well my wife has trouble getting my attention (thats another reason why I like them lol). I would recommend this option.
One final suggestion. During the day when you catch him say nearby, have a gentle chat with him and tell a white lie, that you had children over the night before and they heard you swearing. Say something like this-
"I hope you dont mind me mentioning something as you are a terrific neighbour. I had children over in the evening and they heard you swearing. I told the parents I'll have a nice word to my beaut neighbour about it".
The last 2 I'd carry out before the other police option.
TonyWK
