You don't have to hear through the ear only, in order to be a musician. It's a lot more than that.
I think a great example of that of course is Beethoven. His greatest music was written after he began losing his hearing.
Dame Evelyn Glennie ( Web site) is a Scottish virtuoso percussionist. Despite being deaf since age 12, she learned timpani and percussion and studied at the Royal Academy of Music.
Many composers have written works for her, including James MacMillan, Richard Rodney Bennett, and Thea Musgrave.
Glennie has written music for television, films, and documentaries, and tours regularly throughout the world.
She has collaborated with many musicians including Bela Fleck, Bobby McFerrin, and The King's Singers, and has played with the New York Philharmonic.