Do the alien crew members speak English?

[Orcus]

You're all overlooking the obvious. No one speaks English at all: everyone in the universe speaks American...

 

[DevilEyes]

Does it make any sense to speak of "the Klingon language" as the characters in Star Trek do? That would be like referring to "Human language" or "Terran/Earth language". I guess, thereotically, it is possible that the entire planet is speaking the same language, but it is extremely unlikely.

I will assume that by "Klingon language" they actually meant "the most dominant Klingon language/official language of the Klingon Empire" which in fact has its own Klingon name (which is certainly not "Klingon"), and that by "Bajoran language", "Cardassian language" or "Vulcan language" you all actually mean "one of Bajoran/Cardassian/Vulcan languages".

 

[C.E. Evans]

After all, Starfleet signage and monitor displays are in English. The universal translator is one thing for spoken words...

If the UT alters what you hear in your own head, is it possible it does the same for what you're seeing. That would handle Kirk reading an alien constitution! It would make sense because not all communication is verbal. And McCoy could have injected Khan with a UT, as a standard measure for anyone (human) who didn't already have one.

I believe the universal translator is only an audio device (a hand-held device in the 23d-Century and later a part of a combadge in the 24th-Century) that deciphers spoken words, but not one that rewires people's brains to change what they see. Like I said in the rest of my post that was omitted in your quote, we've seen untranslated languages written.

On a computer display, however, a universal translator can probably convert any language in its database into another.

 

[T'Girl]

In first episode of Enterprise it's stated that Klingons have something like thirty major languages. It was in a couple of Diane Duanes' novels that had the UT injected under your skin, laid against a nerve cluster, it could still be reprogramed and still not always work right.

 

[notwendium]

It makes sense that "Earth English" is "Federation Standard"
Logic follows:
earth starfleet is a department of the UESPA, based in what was the United States and has major member nation-states that speak english as the long-established language (North America, Australia, Britain, etc), therefore it makes sense in a Pre-UT earth for english to be the de facto language of human manned spaceflight.

When earth goes out and makes contact and eventually forms the federation, half the species can't agree with each other, but find humans and earth to be "common ground". therefore the federation starfleet is based there.

Since every organization, UT or not needs a de facto language, the only one to be agreed upon would be English.

It stands to reason that anyone who joins starfleet must know english, if for no other reason then to read static signage/labels, and be able to take/give orders in a crisis when the UT dies.

The exception being a race whose vocal structure precludes them from speaking english.

As for DS9...
Dax speaks English (starfleet member)
Kira speaks Bajoran and cardassian at the minimum.
Quark speaks ferengi (canonically that's it)

 

[T'Girl]

Maybe a good knowledge of basic english, which is why certain slang terms still throw them.