This library noise guide, which turns red if you're being too loud, could be helpful in a ton of other places where you're supposed to be quiet, too. Not to sound like a curmudgeon, but people are too gosh darn loud these days!!!
For kids, you dingbat. What, did you suffer a blow to the head as a child and lose the ability to think rationally?
Take your Soma and be a good little citizen.