When I was little I lived in a caravan - it was a static but all one room rather than separated off. My mum's bed was by the big window and my sibling and I had bunk beds. There was a curtain separating the two rooms (my mum's bed was also the sofa). We moved there when I was 3 and left when I was 7.
My mum used to have quite loud sex in her bed with various men very shortly after putting my sibling and I to bed. I took ages to fall asleep and I would always hear it. I also slept in the top bunk and could see over the curtain 
Thankfully after 7 we moved to a flat and we had separate rooms although she often still had loud sex in her own bedroom and left toys out etc.
Another thread made me think about this as when I lived in the caravan, we lived somewhere that other families lived too, and when I was 5ish another child and I who were roughly the same age used to imitate sex. I've never ever told someone this before and I've always felt very ashamed of it. I suppose it might be linked to what I saw growing up but I've always felt uncomfortable saying that I experienced CSA.
Any thoughts? Is this CSA? Someone posted the traffic light link on another thread and it looks like maybe it was but that's such a scary thing to think aboout.