Just because a baby can sleep through anything, doesn't mean you aren't destroying their sense of hearing.
Do you really think nothing effects your body physiologically when you're asleep?
Exposing infants to loud noises is a form of child abuse, but far more insidious than just hitting them. You are destroying their very means of interacting with the world.
Agreed.
When my cousin was a baby, I was quiet while she slept. Now she's 3 and we're still quiet while she sleeps.
Aside from doing damage, have you any idea how irritable a tired child is?