Simon Cowell Auditions For A Chance To Be Stephen Hawking's NEW Voice
Professor Hawking has had the same trademark voice for 30 years and has now decided it's time for a change.
Simon Cowell is one of a host of celebrities who audition to be Stephen's new voice in aid of Comic Relief.
Watch Stephen view the audition tapes from hopeful celebrities...
You can watch Comic Relief at 7pm on BBC one tonight.