Pronunciation of Adûnaic changed rapidly during its time. Since the phrases and names are given in the Late Adûnaic, this pronunciation guide focuses on that.
Vowels
(A/Â) Pronounce them /a/, in the back of your throat, like the A is in the word “father”.
(Ê) Pronounce them /e:/, in the middle of your mouth. It sounds like the E of “eight”.
(I/Î) Pronounce them /i/, in the front of your mouth, as in the word “machine”.
(Ô) Pronounce them /o:/ as in the word “boat”.
(U/Û) Pronounce them /u/ as in “brute”, in the front of your mouth. Make your lips in the shape of a kiss.
*The circumflex accents on vowels denote extra length on the vowels. Hold the vowels longer. In music this is shown with a tenuto (-) over the note. In IPA, the circumflex accent would be shown with (:).
Diphthongs
(ÂI) Pronounce this /a:i/, as in the word “twine”, except with the A held for a longer time.
(ÂU) Pronounce this /a:u/, as in the word “loud”, except with the A held for a longer time.
(ÔI) Pronounce this /o:i/, as in the word “boy“, except with the O held for a longer time.
(ÊU) Pronounce this /e:u/, a long E, then a short U.
Consonants
(KH) Pronounce it /x/, as in the name “Bach“. Say it in the back of your mouth, it should feel a little as though you are hocking a loogy, or gargling without anything in your mouth.
(L) Always pronounce it as a /l/, as in the word “lear”, never like the L in “bull“.
(NG/NK) Pronounce the N /ŋ/, as in the word “finger” or “thinker”.
(PH) Pronounce it /ɸ/, basically an F, but pronounced with your lips pursed, instead of your lower lip pressed against your upper front teeth.
(R) Pronounce it as an /r/; roll it as we sometimes do in the word “growl” If you can’t roll an R, like me, make an H sound with your throat closed a little. It should make a rolled A sound. It’ll be a little like gargling water.
(TH) Pronounce it /θ/, as in the word “nothing”.
(KKH) Pronounce it /xx/, ending one syllable and starting the next one.
(PPH) Pronounce it /ɸɸ/, ending one syllable and starting the next one.
(TTH) Pronounce it /θθ/, ending one syllable and starting the next one.
(PTH/PHD/PHT) Pronounce it /ɸθ/, ending one syllable and starting the next one.
(KTH) Pronounce it /xθ/, ending one syllable and starting the next one.
The rest of the letters are pronounced as we pronounce them in English.
Source:
The Lord of the Rings (The Return of the King) – Appendix E
Sauron Defeated – The Drowning of Andûnê – Adunaic