While working on speech synthesis for the Massachussets institute of Technology Researcher Dennis Klatt produced a speech synthesiser algorithm called Perfect Paul. This software algorithm took recorded speech and used its sounds and parameters to create rules which could generate synthesised speech from text. The recorded speech it used to generate these rules were hours and hours of Dennis recording his own voice.
The algorithm was to be used by the Speech Plus CallText 5010 speech synthesiser being developed at the time.
Stephen Hawking would start to use the CallText 5010 speech synthesiser in 1985 when an emergency tracheotomy left him unable to speak. With this subsequent adoption of speech synthesis Dennis Klatts computer generated voice would become the voice of Stephen Hawking and would be recognised around the world.
Stephen Hawkings equipment would be upgraded throughout his life but he would always use the Perfect Paul algorithm so that he could keep ‘his’ voice which in later years would become as famous as he was.
Dennis Klatt would sadly develop Thyroid cancer which would affect his vocal chords causing him to lose his own voice before he passed away in 1988