Tibetan Za ཟ

Za is the twenty-second of the thirty consonants and, in the classical language, the voiced alveolar fricative, the z of English zoo. In modern Lhasa speech it is devoiced toward s and is distinguished from sa by low tone rather than by voicing.

Za is the plainest single illustration of the largest sound change between the language the alphabet was designed for and the language spoken in Lhasa today. Two letters that once differed in the vocal cords now differ in the pitch of the voice, and no distinction has been lost, only moved. The spelling has not followed the change, which is why written Tibetan looks so much more conservative than spoken Tibetan and why the tone of a syllable is largely predictable from how it is written.

The change is not universal across the Tibetan-speaking world, and the article beside this one takes up what that means.

Za takes superscripts and the wa subscript. It is not a prefix, not a suffix, not a superscript and not a subscript, so it belongs entirely to the recitation and to the root of a syllable.

As an initial it carries low tone in modern Lhasa speech, in company with the other letters that were voiced in the classical language. The pair za and sa is one of the clearest places to hear what the tone system is doing, since two syllables built on them can differ in no consonant and no vowel and be told apart by pitch alone.

Almost every general statement about how Tibetan is pronounced is a statement about the speech of Lhasa, and Lhasa is not Tibetan.

The Tibetic varieties spoken across the plateau and the Himalaya differ from one another at least as much as the Romance languages do, and they are not mutually intelligible across the range. The central varieties around Lhasa, which supply the standard, have lost the initial consonant clusters the spelling records and have become strongly tonal in compensation. The Amdo varieties of the northeast have gone the other way: they retain a great deal of the old cluster system and are correspondingly less tonal, so a word written with a prefix or a superscript may still be pronounced with the consonant the spelling shows. The Khams varieties of the east differ again, and Ladakhi and Balti in the far west retain archaic features of their own.

The written language is shared. All of these varieties are written with the same thirty letters and the same spelling, which is one reason the spelling has not been reformed to match any single pronunciation: it is the common property of speakers who could not otherwise read one another.

So the silent letters are not silent everywhere. What Lhasa speech has spent, other Tibetan speech is still using, and the alphabet is closer to some living varieties than to the one usually described.