Bob Moog built a Vocoder, which this really is but under a souped up 2000s name, in 1968.
Hi, Eddie.
Vocoding takes a "real" voice and uses it to modulate audio. It's a transformation of the original sound.
Voice synthesis is creating a new vocal from scratch, where you can enter lyrics and pitch information, and the computer generates the vocal without human intervention.
Computers driving a vocoder
are one way of generating that sound.