Re: So the sounds, but what about the content.
In 1981 or so... just before CD's came out to the general public, a dozen or so of us music students were dragged down to Universal Studios (famous in Chitown) and brought into two engineers booths. In the first one they said to "listen to this". We then moved into the booth next door and they said "now listen to this". We all agreed the first one was better. Much better.
It turned out the first one was analogue recording, the second one was the same recording converted to the new CD format. Granted we were all *seasoned listeners, but that is the point. Since digital recording (albeit the early ones were the worst) there are pieces of the spectrum that just aren't heard and therefore not really expected or trained to be heard by anyone in the general public, and haven't now for the most part of the last 40 years. Generally its the existence, not as primary, but clearly some flavor, subtlety adding overtones and timbre missing which today nobody is aware of its lacking.
The voice is a quite complex sound and the nuances of language, timing and timbre is, as far as I'm concerned, best left for humans to experience with others.
Saying "machine voices outsmart us" is as relevant as "is it live or is it Memorex?".