deaf or muzzle?

I have never ever wished I was deaf before. You know how people will ask, if you had to be blind or deaf which would you choose? And I usually went with blind because I don't know if I could give up music, the noise of the ocean and other such sounds.

However, I was willing to give all of those lovely noises (buh-bye to thunder, the rain, Radiohead and Moby) up if it meant I was deaf to the screechings of a young child. Every time they would open their little mouth, I would involuntarily shiver, tense up and want to tell off the said child and parent. Why do parents think it is ok to allow their children to scream at the top of their lungs? Do they become immune to the god awful noise? Is that what happens when you become a parent, you just zone out your kid? Since it is ok to muzzle dogs, why can't we muzzle kids?