[rspeer]

Without the "intelligible" part, this makes me think of what the game Celeste does to give its characters voices without voice acting.

They make voice-like synth sounds, different for each character, that are about the length of the text they're saying. It adds prosody and intonation to the text-based dialogue of the game.

https://youtu.be/TZpQH8kSWNU?t=2m50s

[andai]

This is how I imagine an intelligent car would sound if it figured out how to produce speech through the antigravity engine.

Edit: oh sweet there's intonation too. Were these all made manually?

[rspeer]

My guess is they're mostly procedurally generated with manual tweaks for particularly significant lines.