Concerned and not sure how to handle situation

I am new to this site and am hoping this is being posted in an appropriate place.. I live in an attached townhome and the walls -we discovered AFTER moving in- are very thin. I can hear what goes on next door all the time. There is a family of 4 living next to us. Husband, wife and 2 kids. I believe the 2 boys are around the age of 3 and 6. The problem is that I believe there is a level of verbal and emotional abuse going on. I always hear the mom yelling at the kids. Cursing A LOT! "f" this "f" that "f-ing shut up" she is saying this to her children all the time. She complains to them about her problems as if they are adults. When she talks to her husband on the phone and they fight she does not leave the room, she yells at her husband in front of her kids. "your stupid" "your pathetic" and so on. They constantly fight when they are both home and they argue right in front of their children. I can hear the kids in the same room as they are in. The father seems to be less aggressive than she is. And have never heard him behave this way to the kids. I never hear anything "happy" going on over there. I can sometimes hear the kids playing amongst themselves but I never hear happiness between mom and children. Sometimes I think it is crazy that I hear this stuff all the time and that I should do something. But what?? Call police or CPS? and say what? I have no proof of anything, what if someone makes a "visit" in response to my call but nothing happens? then I have to live next door to her and she will know it was me. There is noone on the other side of them. And is there really anyway to be 100% annonymous in that situation? If someone went to their house, what would they say "someone heard you"?? GEE, I wonder who that would be?? Maybe I should mind my own business.. But I cant help but feel terrible for those children.. What would you do in my place?