Quies
Well, I have taken my kids in all classes long haul, and been a victim of screaming babies in all classes too, once with a (?) Philippina nanny and two googoos in First. I think the reason there are more babies - proportionately - in Economy may just be that there are more seats. Two notes:
1. When there is no noise left in your life, that is because you are dead.
2. The most effective ear plugs I have found are the "Quies" wax ones. You do have to remember to remove the cotton that covers the wax. In extreme cases, leave your headphones on.
Other suggestions for artificial silence?
Momo