No aibu by stealth here, full disclosure up front: I don't have kids of my own so I appreciate that I can't fully put myself in their shoes. Also my parents shouted at my siblings and me plenty of times when I was a kid including quite a bit of swearing/proper angry shouting from my dad, but as a child of the 80's I was also smacked which is generally frowned upon now so I realise that perceptions of these sorts of things do change.
My neighbours have two little boys that I think are around 4yo and 6yo. From what I've seen they're pretty typical boys with a lot of running around, active play, questioning and pushing boundries so I can well imagine that they'd be a handful and some shouting is to be expected. But I can't see how yelling "shut the fuck up", "fuck off back to bed" and "I'm going to give you a fucking smack in a minute" on quite a regular basis can really be helping.
I'm sure both the mum and dad love their kids as much as anyone, and I haven't seen or heard anything that would suggest there's any physical violence or abuse going on, but it's quite difficult hearing this shouting and swearing directed at two quite young children every day or every other day.
I'm not on much more than nodding/saying hello terms so it's not like I can casually ask them "how are things, because I couldn't help overhearing you were really screaming at X last night". I know they've got a lot of extended family/friends in the street and the wider area who regularly come over to visit so I don't think they're lacking a support network, and as I said I'm the childless neighbour on nodding terms so I doubt they'd take me up on a babysitting offer to give them some more time to themselves.
I am trying not to be that grumpy judgey neighbour, and this is nothing to do with the noise/shouting itself because I really like seeing all the kids out playing on the green (it's a cul-de-sac) and they seem like nice boys who always wave and shout hello when they see me; I'm just really not sure if I should be doing anything about this swearing or if I should just shut up and mind my own business because it's nothing to do with me. Help?!