Michael Chorost would like to listen to Ravel’s Boléro. But since 2001, when the last of his already feeble hearing left him lost in a soundless world, he hasn’t been able to. Chorost has been a guinea pig at the forefront of the cochlear implant industry, which uses surgical implants and computer technology to allow deaf people to “hear” by stimulating certain parts of their nervous system. But while such technology can allow the deaf to decode human speech, music is a wholly different (and far more complex) matter. Still, Chorost is a determined music lover, and years of trial and error eventually lead him to a breakthrough. “It’s like going from being able to tell the difference between red and blue to being able to distinguish between aquamarine and cobalt.”