Neighbours - at what point do you ring the police?

[Teacuphiccup]

I was wondering if someone could give me some advice.
My next door neighbours are a big family and they are quite noisy which has never really been a problem except the oldest son has just had a baby and when it comes to visit, him and the mother have the most horrendous rows I’ve ever heard.
Today they were screaming at each other so loud the whole house was shaking and there kept being foundation rattling thuds and bangs.
Obviously I can’t see what’s going on so I’m not sure if he’s hitting her or punching the walls, i can just hear what’s coming through the walls but it was very frightening, my dad used to beat up my Mam when I was little and I can’t tell if that’s clouding my judgement but I would have rang the police today but just as I picked up the phone he got in his car and spend off.
I don’t want to put my nose in but I would never forgive myself if something happened to someone and there’s babies in the house.
But I also have to live next door to them and it would be obvious who rang the police.
At what point do you think you should ring the police when you can hear an argument?

Sorry that really needed some punctuation

I would have no issues with ringing the police in this situation.

I'm in a similar situation. I've been toying with the idea of calling the police for ages. I just don't know what to do.

I would definitely ring 101. It might not be an emergency, but it gives you somewhere to put your concerns.

I did this once after witnessing something in a supermarket. It was taken really seriously and they contacted the store to get the CCTV footage.

I'd call the police next time, let them sort out if physical violence is part of it. Definitely sounds like an extremely unhealthy environment for a baby to be in and you're only hearing the part that happens when they visit there, God knows how bad it is in their own home.

Oh to clarify the older son lives next door and the baby and mother visit.
They don’t live together, thank god.

Given what you've described, i would call the police as soon as the shouting starts.

Why 101 and not 999 as it happens?

If it’s loud enough for you to hear , then ring . If it’s really loud as you describe and both parties are present , then there’s no reason not to call 999 if you are fearing violence is going on .