There is also a good chance someone can learn to encode quite a bit into vocalizations.
Anyone who seriously learned an instrument or to sing, knows that it takes very hard practice for years to improve.
Yes, but vocalizations may well improve more quickly.
Frankly, I have toyed with this kind of thing. Software could do a lot, in particular, allow the user to adapt their expressions in various ways.
There is also a good chance someone can learn to encode quite a bit into vocalizations.