How does Stephen Hawking talk ?
Who is not aware of this living computer ? Well, everyone more importantly space scientists and science students know what sort of a genius he is. He is known for his papers on black holes and his researches on Quantum gravity theories. All this he does sitting on a wheel chair. You cant even imagine how genius he really is. He is a professor of Mathematics at Cambridge University, and the director of research at the school's Center for Theoretical Cosmology.
He suffers from a disease called ALS - amyotrophic lateral sclerosis which means your respiratory system will crash, your muscles will be like swallowing and you will not be able even move your neck or legs whatsover. And eventually you will have to die in 2 to 3 years. But, this guy is an outlier. He has survived for decades.
Not only that, he is able to communicate with the help of a synthesizer and a sensor which tracks the face movements and translates it into words. He has got a small button attached to his seat which he presses to confirm the words. LIn this way, he is able to communicate with others. He can talk upto 15 words per minute. With the help of this machines, he has given hundreds of lectures, authored two books , given lot of interviews. Intel and Lenovo are the key technology partners who have provided this technology to him.