Which short story am I thinking of?

It's been quite a while since I read it, so I cannot remember the fine details, but there are a few I can recall. I know that it was set in a dystopian society in which everyone is forced into being identical; those who are too clever or too strong are given mental or physical handicaps to bring them down to the same level as everyone else. I don't remember the plot, but I remember that the main character was a man who was given a mental handicap- when he began thinking too much into things and questioning society, he could hear things such as ringing in his ears to distract him from it all. And, I remember that it began with he and a girl (I think it was his sister?) sitting and watching television together.
I'm sorry, I know that is extremely vague but I've been wondering about this for quite a while and can't remember what it was called for the life of me. I'm thinking it has to be relatively well-known, as I first read it in an English book I was assigned in school.
Thanks