Númenórean Sindarin

"Many used some other tongue than the Common Speech, but it was not long before he learned at least what was meant by "Ernil i Pheriannath"..."

― Pippin in Minas Tirith

Gondor Sindarin was a dialect of the Elven language spoken by the Men of Gondor.

Differences

Westron was the first language of Gondor. The nobility usually learned Sindarin, and used it to be polite to other nobles and strangers alike. Because it was both an acquired and a learned language, it had some notable differences with "regular" Third Age Sindarin.

Phonetical

Like any acquired language, the second language's sound range is directly influenced by the speaker's original sound range. Westron did not possess ch or y, and pronounced them differently.

"Y"

The y was pronounced by Sindarin Elves as IPA [y], a close front rounded vowel. Of all languages, only Sindarin had this sound, so it was problematic for speakers of other tongues. Gondorians generally pronounced it as an i, though it was sometimes substituted with an e, as in the Gondorian plural for onod, ened (rather than the usual enyd).

"CH"

Also frequent in Sindarin was the ch, the velar fricative, which the Gondorians also encountered among the pre-Númenórean dialects placenames as Erech and Eilenach.

The most notable use of the voiceless velar fricative was in the name of Gondor's new northern neighbour, Rohan. Originally envisioned as Rochand, in Gondor this became Rohan, and though the tongue of the Éothéod did possess the voiced ch, it adopted the southern use. The voiced velar fricative, which is found in Rochand, was pronounced as a sounded h, while the voiceless variant, at the end of words, was pronounced as a k. Those very learned would pronounce them correct, but forcibly so.