On Stargate SG-1, Daniel Jackson was recruited for the team mainly for his knowledge of ancient Egyptian and other ancient languages, and his ability to read “Ancient.” So, unlike some SF settings, this one acknowledges that languages other than English exist. Well and good. But why is it that wherever they go, to any other planet, or even another galaxy in the Atlantis series, every sentient being they encounter, human or nonhuman, speaks perfect English with an American anchorman-standard accent? (Except when someone speaks a strange word that refers to some concept unique to the local culture.) And the SG-1 team apparently has no “universal translator” machine and no babel fish or injected translator-bacteria to explain this convenient phenomenon. What gives?
It’s a plotting thing…they got tired of having Daniel translate to and from every. Single. Person. They. Met.
I liked that touch, but it got annoying after a while.
Yup, Daniel is the universal translator for SG-1. It got boring watching him translate all the time so now you should just rest assured he’s there, translating (even if it appears he’s not even in that scene, he’s still there. He just is. Get over it.).
Seeing the thread title made me think immediately that they had neither of these devices in evidence on the show.
So I suppose we should assume Daniel translates everything, much like WWII films where Nazi’s come on screen and talk German for a few seconds then revert to English with a German accent, just to let us know that they’re speaking German really but we the audience don’t have to worry about subtitles 
They pulled that stunt with the Russians in Hunt for Red October, too. Pissed me right off, that.
Well, that works, except for season six.
But see, that’s how he does it. After his ascension he goes back in time and rewires everyone’s brain–including his own–to serve as a universal translator. He also rewires them to be unaware of the rewiring, and to be unsurprised that every alien culture speaks flawless, american style english.
The translation is performed automatically by a field generated by the Tardis – a technology powerful enough to cross series’.