I mean, to be fair, the further you get into portal, the less AI Glados sounds (By design) and wheatley never sounds like an AI (by design).
There are definitely ways of making human voices sound like AI, but they are exercises in audio crafting and are by no means easy. For example:
View: https://music.youtube.com/watch?v=lp-rUnoJH3w&feature=share
TL:DR - it's hard, and that's good. Let masters of their craft continue to interoperate that good folly.
It's actually interesting how quiet Capcom has been about the voice acting in exoprimal considering SF6 has their voice actors prominently displayed on the game's website., but I'm pretty sure Leviathan in the english version is not AI. The writing for the character is actually pretty cutting against AI integration (as it would be for the plot of the game, but still).