I recall that the "say" program on the SGI from the mid 90's was approximately Hawking's voice. Hawking gave his speech for the Whitehouse Millennium Lecture at SGI also, and while I wasn't able to attend I found the transcript of it and fed it in there... there were some jokes that he had that only really came through with the intonation and pacing of a voice synth -- its the ultimate dead pan voice.

https://clinton.presidentiallibraries.us/items/show/16112 https://youtu.be/orPUQm1ZRSI

And his voice was his - even with the American accent.

https://www.news.com.au/technology/innovation/why-stephen-ha...

> “It is the best I have heard, although it gives me an accent that has been described variously as Scandinavian, American or Scottish.”

> ...

> “It has become my trademark and I wouldn’t change it for a more natural voice with a British accent.

> “I am told that children who need a computer voice want one like mine.”

Somewhere, I recall a NOVA(?) program from the mid 80s where it showed him using the speech synthesizer and the thing that he said with it that still sticks in my mind is the "please excuse my American accent". In later years he was given the opportunity to upgrade it to a more natural sounding voice - but that voice was his.