I just want to point out that often normal every day living can unintentionally make a lot of noise in the basement. I lived in a basement for a few years and had a lot of noise and I have no complaints against the guy because I realize that little things like moving around chairs and vacuuming are normal usage and can sound very loud downstairs when he has no clue what it sounds like.
Now rollerskating indoors on the other hand....
My best eitza is that next time there is a lot of noise, ask him (non-confrontationally) to come downstairs and hear what it sounds like. It may be an eye (ear) opening experience for him.
+1
FME and from speaking to my friends, it seems like every basement has noise.
My landlord has a very active 5yo boy, and they told us straight out that they try quieting him and they feel bad, and if it ever bothers us we should just bang on the ceiling with a broom. The problem is that it's pretty constant and we're embarrassed to constantly complain. So we don't have anything against them; we'll either just bear it, or move soon to an upstairs apartment.
Of course, if your situation is where they're doing something abnormal, that's different.