Child Abuse?!

So this has been happening for a while but I'm not sure what to think or do about it. My upstairs neighbors that live diagonal from us (I've never seen or met them at all) have a toddler it sounds like; And from about 10am to 2pm every other day, I'd hear very loud cries and screams.. Followed by a very distinct "SHUT UP!!" and a very loud bang or thrashing sound.. THEN followed by a hurtful cry/scream... And more louder banging and thrashing sounds.

Now my first thought was that this woman is beating her child. Because the cries don't sound like normal cries (for example, a cry for food/milk) it sounds like cries of pain... And I'm sitting there cringing because it makes me sick and feel sorry for the child. Friends that have stayed over have heard it as well and agree with me. The thing is.. what should I do? I'm not absolutely 100% sure if this is really happening or if I'm just thinking for the worse. I don't wanna report it and then it happens to be a false assumption. :/

Or it could possibly be a babysitter and not the actual parent that's abusing the kid... Which is just as terrible.

If it continues though, I just might report it, regardless.