Please don't. I have yet to hear any Text-to-Speech system that doesn't sound completely terrible, and it will probably still take at least 2 decades until the technology is refined enough.
I don't want to bring up that immersion stuff but voice synthesizers would be a reason for me to switch off the sound or uninstall the game. Just leave it as it is and maybe add some lines with real voice actors.
If you could apply filters/effects (such as the natural compression artefacts you get in digital comms) these would hide the "artificialness" of the voices. Assuming they wouldn't add too much of a performance penalty.
If I am not completely wrong, the current ship voice is already synthetic.
At one point during the beta phase (for 1.0), the voice changed considerably. FD's comment on this was, that the new voice grants them greater potential (or something alike).
I think, the "original" voice was recorded, the new one computer generated.
If this assumption of mine(!) is indeed true, all sorts of usage should be already possible... at least in principle.
That's what predefined voice command macros are for. (And, yes, I realize how bizarre it is to speak a command that types words for you because you can't speak to another commander)I mean who in their right minds bothers to type messages to you when they are under attack and need saving.
A lot of programs do it in a ok way, of course they sound a bit robotic however that is just fine by me.
We use it is flight sims all the time, and together with voice recognition you soon forget the mechanic voice, and just go along with it.