Neighbors with loud children?

We live in what would seemingly be a quiet neighborhood with large, secluded, wooded lots. We have neighbors that have 6 or 7 kids. Another neighbor told us that they're Protestant Reformed and this has something to do with the large family. I realize kids need to play and be kids, but there are a couple of them that scream at the top of their lungs constantly. I do mean constantly. They're outside all day from morning until after dark screaming. My guess is that it is for attention. With that many kids how could one possibly ensure that each gets enough attention? It has disrupted many many evenings and sunny Saturdays. Again, the important part is that It is not just for an hour or two - it is all day. I envision that their mom kicks them out of the house, closes windows and doors and throws on her ipod and enjoys her peace. I can't see their yard so I really have no idea if they're supervised by a parent or turned over to an older sibling. This is the interesting part - Most people look at me like I'm crazy when I mention that these kids are bothersome, until they stop by for a visit. Then they make comments like "they sound like wild animals" and "I could not stand this constant yelling." The people that make these comments are parents themselves. We've never met these neighbors and I fear writing a respectful note or paying a visit would do nothing but cause retaliation. If your response is just going to be "get over it" please don't bother. Like I said I understand that kids need to be kids, but this is a neighborhood and other people live here and I think there should be limits. It's not a park or campground and allowing screaming all day long seems rude. On a side note we have 2 large beautiful parks within less than a mile, they could easily load them up. I've considered a radio to help drown them out but then I'm just adding to the noise. Is a respectful note even feasible? Would it just ensure retaliation? I know if I were bothering someone and received a respectful note ("respectful" being the key word) - I would feel bad that I've caused someone grief.