The language spoken in Deverry is a member of the P-Celtic family. Although closely related to Welsh, Cornish, and Breton, it is by no means identical to any of these actual languages and should never be taken as such.
Vowels are divided by Deverry scribes into two classes: noble and common. Nobles have two pronunciations; commons, one.
A as in father when long; a shorter version of the same sound, as in far, when short.
O as in bone when long; as in pot when short.
W as the oo in spook when long; as in roof when short.
Y as the i in machine when long; as the e in butter when short.
E as in pen.
I as in pin.
U as in pun.
Vowels are generally long in stressed syllables; short in unstressed. Y is the primary exception to this rule. When it appears as the last letter of a word, it is always long whether that syllable is stressed or not.
Diphthongs generally have one consistent pronunciation.
AE as the a in mane.
AI as in aisle.
AU as the ow in how.
EO as a combination of eh and oh.
EW as in Welsh, a combination of eh and oo.
IE as in pier.
OE as the oy in boy.
UI as the North Welsh wy, a combination of oo and ee. Note that OI is never a diphthong, but is two distinct sounds, as in carnoic (KAR-noh-ik).
Consonants are mostly the same as in English, with these exceptions:
C is always hard as in cat.
G is always hard as in get.
DD is the voiced th as in thin or breathe, but the voicing is more pronounced than in English. It is opposed to TH, the unvoiced sound as in th or breath, (This is the sound that the Greeks called the Celtic tau.)
R is heavily rolled.
RH is a voiceless R, approximately pronounced as if it were spelled hr in Deverry proper. In Eldidd, the sound is fast becoming indistinguishable from R.
DW, GW, and TW are single sounds, as in Gwendolen or twit.
Y is never a consonant.
I before a vowel at the beginning of a word, is consonantal, as it is in the plural ending -ion, pronounced yawn.
Doubled consonants are both sounded clearly, unlike in English. Note, however, that DD is a single letter, not a doubled consonant.
Accent is generally on the penultimate syllable, but compound words and place names are often an exception to this rule.
I have used this system of transcription for the Bardekian and Elvish alphabets as well as the Deverrian, which is, of course, based, on the Greek rather than the Roman model. On the whole, it works quite well for the Bardekian, at least. As for Elvish, in a work of this sort it would be ridiculous to resort to the elaborate apparatus by which scholars attempt to transcribe that most subtle and nuanced of tongues. Since the human ear cannot even distinguish between such sound pairings as B> and B<, I see no reason to confuse the human eye with them. I do owe many thanks to the various Elven native speakers who have suggested which consonant to choose in confusing cases and who have labored, alas often in vain, to refine my ear to the Elven vowel system.
A Note on Dating:
Year 1 of the Deverry calendar is the founding of the Holy City, or, to be more accurate, the year that King Bran saw the omen of the white sow that instructed him where to build his capital. It corresponds roughly to 76 C.E.