As readers of this blog can tell, I'm very interested in the origins of just about everything, particularly when it relates to music.
The first electronically synthesized speech was created using an analog device, the "Voder", which was demonstrated at the 1939 World's Fair.
Digitally synthesized speech probably originated at Bell Labs in 1962 on the IBM 704 computer. These computers had an estimated 18 bytes of memory, and were the first to use core memory rather then tubes to store binary information.
The song "Daisy Bell", also known as "A Bicycle Built for Two", was digitally synthesized by John L. Kelly, with accompanying music by Max Mathews. It was a major moment in computer history.The writer Arthur C. Clarke was present at this demonstration, and used it in "2001: A Space Odyssey", when the HAL 9000 computer sang it.
The Wikipedia article on the IBM 704:
An article by Bell Labs on text-to-speech synthesis:
A photo of an IBM 704:
Daisy Bell", "sung" by the IBM 704.
The notes here refer to the computer used as an IBM 7094, a later model. It seems that the IBM 704 however was in fact the computer used, since it's referred to that way in the Bell Labs article.
Computer speech from Bell Labs - this also includes "Daisy Bell"
Some music from the "Music for Mathematics LP". The cover for this LP was designed by Alex Steinweiss, the first album cover designer.