Alright, fluffy people of Mastodon. (by Fluffy I don't mean fat, just, fluffy, you know, friendly and fun.)
DoubleTalk PC really did use human speech. It's a 356 kilobyte LPC waveform. And it sounds like this, if you played it back. Just a bunch of garbled greatness. What's amusing to me: Someone had to do this sort of chant at a constant flat F0, never adjusting their pitch, and then they packed that into a rom. And this was 1988, so anything more than 1 megabyte of storage is a stretch, so they did what they could.