Today, at 69, Dr. Hawking is one of the longest-living survivors of A.L.S., and perhaps the most inspirational. Mostly paralyzed, he can speak only through a computerized voice simulator.
On a screen attached to his wheelchair, commonly used words flash past him. With a cheek muscle, he signals an electronic sensor in his eyeglasses to transmit instructions to the computer. In this way he slowly builds sentences; the computer transforms them into the metallic, otherworldly voice familiar to Dr. Hawking’s legion of fans.