Swearing is totally irrelevant when the baby is 6 months (and there's an argument to say it is irrelevant whenever, words are just words etc).
Shouting and anger directed towards a baby is a real issue. The baby will be scared.
I HATE shouting and anger, I'm hypersensitive to it. My other half often raises his voice or expostulates loudly when he's frustrated, and thinks I'm bonkers to be so bothered by it and inhibiting his natural expression of his feelings. I think he's half right, and so am I
It's a pretty constant bone of contention...
But he doesn't ever, shout at our baby (and she's a pain at the moment, proper case of the four month fussies). In fact, if he hears me getting frustrated with her (which I sometimes do at the end of a long day of moaning and constant diversion), he comes and takes her off me, because he knows it's not good for her or for me. Shouting at a baby is just horrible.
I read in one of my baby books that something like 75% of parents surveyed admit to having smacked their baby before they're one year old. I was HORRIFIED by that statistic. I think with that in mind, you should nip this in the bud straight away, as if he can't control his anger manifesting in this way, there's no way you can be sure where he will draw the line as your boy becomes bigger and still more challenging.
You should have a serious chat with him about your concerns re his mental health and how he's adapting to your new life with the baby - suggest he approach his GP, or if he shies away at that as men are wont to do, maybe suggest you both enrol on a parenting course? It's a huge change, and hard to do in a small flat (as we are learning!!) as you can never really 'get away'. But the first thing you need from him is agreement that growing up with anger and shouting is not an acceptable environment for your little boy. Only if he can be made to see it is a problem can you work together to solve it.
In the meantime, every time he raises the volume around your baby, remove the baby. Get as far away from him as you can in your small flat as you can and shut the door. He needs to learn that if he wants to parent his son, he has to be able to control himself. It will add to your workload and it isn't fair; but it has to be done. Good luck!