The man who helped upgrade Professor Stephen Hawking's iconic voice says "it died with him".
The world-famous physicist died at his home in Cambridge in March at the age of 76.
Peter Benie, a Cambridge University officer, told the BBC: "One of the most recognisable voices on the planet is Stephen Hawking’s.
"Shortly before he died, Stephen approved and used a new version of his iconic voice that precisely replicated it.
Scientist Stephen Hawking - In pictures
"I was part of the team that developed this updated version by mirroring the original hardware."
Mr Benie said the original hardware used to produce Prof Hawking's distinctive voice needed replacing after 30 years.
"Stephen remained steadfastly loyal to what had become his authentic voice...He didn’t want it changed in any way.
"I’m proud to be part of the team that preserved his voice. The voice is part of his identity - you wouldn’t use it for someone else - so effectively the voice died with him."
He said that although Prof Hawking used the upgraded version in private with friends and family, he never got to try it out in public.
