Kirk was never shown to have a head for languages, though.
In ST3, Kirk apparently
doesn't speak any Klingonese - in order to get beamed up from the dying planet, he has to try and imitate the one word he has overheard ("Jooooichu!") and hope that it works. He doesn't look as if he
understands what he's saying. He's merely going monkey-hear-monkey-say, doing a passable but imperfect rendering of two syllables. This after spending a lifetime at war (cold or hot) with the species. ST5 and ST6 only confirm he doesn't get Klingon jokes...
Hey, even Uhura doesn't know much of the language, as we see in ST6. And she is a communications specialist. Obviously, something other than mere linguistic skill is used as the preferred means of communicating with alien species. So, even if we don't hear of UT implants in the TOS era, it seems pretty clear they are already a fixture.
Which helps explain this one:
If we're going to get nit-picky, I'm always bothered by the fact that with a UT, why the Hell aren't the words and lip movements out of sinc?!
If the UT is an implant, then it probably isn't an "internal loudspeaker" at all. It doesn't translate sound. Rather, it translates neural signals after the ear has picked them up.
If the brain keeps hearing English (and here we assume the audience is wearing UTs as well), it is likely to automatically adapt and start
seeing English, too. The one thing that the brain does well, and probably is primarily built for, is deluding itself.
If this isn't enough, then the UT implant could fiddle a bit with the visual signal processing in the brain, too. Nothing as clumsy as creating false signals of English lip movements. No, much better to let the brain do the translating, and merely send subtle cues that tell the brain to ignore the original lip movements and substitute its own, better fitting ones. We could probably do that today, with a little effort.
Timo Saloniemi
And also, Kirk has a knack for languages. In TSFS, after hearing Kruge say a phrase in Klingon once, he repeats it a few minutes later, with such good pronunciation, that the Klingons beam him up to their ship!
