Michael Chorost was born with a severe hearing impairment, the result of a rubella epidemic in the 1960s. He used hearing aids, learned to speak, went to regular schools and got his Ph.D. in English. Then, a few years ago, Michael's residual hearing abruptly gave out. His world went silent. Jocelyn Gonzales has the story of how Chorost replaced his lost sense of hearing with an amazing machine.