The sounds ch (German ach-Laut, NOT "tsh" as in English church) and th, dh ("th" as in think and this, respectively) are frequent.

The unvoiced plosives p, t, c never occur following a vowel, but are lenited (see class) to b, d, g.

c is always pronounced k (standard example: Celeborn = "Keleborn", not "Seleborn").

At the end of words, f is pronounced v, as in English of. (In Tengwar spelling, a word like nef is actually spelt nev.)

R should be trilled, as in Spanish, Russian etc.

The digraphs rh and lh represent unvoiced r and l (but sometimes these combinations may actually mean r + h or l + h, as in Edhelharn - not surprisingly, our alphabet cannot represent Sindarin quite adequately).

Sindarin has six vowels, a, e, i, o, u and y, the last of which corresponds to German ü or French u as in Lune (pronounce ee as in English see with rounded lips as when you pronounce oo, and you've got it).

Long vowels are marked with an accent (á, é etc.), but in the case of stressed monosyllables the vowels tended to become especially long and are marked with a circumflex: â, ê etc. In html one unfortunately cannot place a circumflex above the vowel y. To avoid ugly spellings like my^l ("gulls", WJ: 418), we here use an accent instead (the relevant words occurring in this article are býr, thýn, fýr, rýn, mrýg, mýl, 'lýg and hýn - ideally these should have had a circumflex instead). This is not very critical: In Tengwar writing, no distinction is made between long and super-long vowels; the use of circumflexes instead of accents in monosyllables is merely an extra complication Tolkien introduced in his Roman orthography for Sindarin (evidently to make it abundantly clear how the words are to be pronounced).

The Sindarin diphthongs include ai (as in English aisle, NOT as in mail), ei, ui (as "ooy" in too young) and au (as in German Haus, or as "ow" in English cow). At the end of words, au is spelt aw.

There are also the diphthongs ae and oe, with no English counterparts; Tolkien actually suggests substituting ai and oi if you don't care about such details (indeed he sometimes anglicized Maedhros as "Maidros". Ae and oe are simply the vowels a, o pronounced in one syllable with the vowel e (as in English pet), just like ai and oi are a and o pronounced together with i. Somewhat confusingly, in Tolkien's writings the digraph oe is sometimes also used to signify umlauted o, apparently the same sound as German ö. By the end of the Third Age, ö had merged with e (that's why the Grey Mountains appear as Ered Mithrin and not Öröd Mithrin on the Map to LotR!), but we still need to refer to this sound when discussing archaic Sindarin.

From the Ardalambion, The Noble tongue, (pronounciations)