How does Earendil speak Beorian?

[Galin]

Originally Posted by Galadriel55

( . . .) If Tolkien's ever said anything on the matter of these languages, I've forgotten, but my headcanon was that the Mannish tongues were related to each other - if not different dialects of the same speech, then languages of the same family. Similar to the different languages/dialects of Elvish. And at least between the people of Beor and Hador there seemed to be enough connections and intermingling throughout history to make it plausible that the two languages did not drift that far apart.

In The Problem of ROS itself, the speech of the Hadorians is said to be related to the tongue of Beor's folk: "(probably about as nearly as Noldorin Quenya to Telerin of Valinor): communication between the two peoples was possible but imperfect, mainly because of phonetic changes in the Beorian dialect."

Here it's added that the language of the folk of Haleth, "so far as it was later known, appears to have been unrelated (unless in remote origin) and unintelligble to the other peoples."

The essay goes on to say that the folk of Beor continued to speak their own tongue among themselves with fair purity, though many Sindarin words were borrowed and adapted by them. "This was of course the native tongue of Beren . . ."

Emphasis on the scenario as described in this late essay at least!

A note adds that the Halethian language was already failing before Turin's time, and finally perished after Hurin in his wrath destroyed the small land and people.