Tibetan Cha ཆ

Cha is the sixth of the thirty consonants and the aspirated partner of ca, the same palatal affricate released with a breath. It is a root letter with no orthographic duty: not a prefix, not a suffix, not a superscript, not a subscript.

Its interest is in how neatly it confirms a pattern. In modern Lhasa speech ca and cha have converged as a single aspirated affricate carrying high tone, exactly as ka and kha have converged in the line above and ta and tha will converge in the line below. The convergence is regular enough that a reader who knows what has happened to one line can predict what has happened to the others, and this is one of the reasons the alphabet is taught as a grid rather than as a list. The columns behave, and behaving is what makes them learnable.

The regularity also explains why Tibetan spelling looks harder than it is. Two letters that now sound the same are not an arbitrary redundancy; they record a distinction the language made when the script was designed and which a good many Tibetan speakers outside Lhasa still make. Spelling has kept a contrast that the prestige dialect has spent, and the alphabet is in that sense a document of the seventh century rather than a description of the twenty-first.

The largest single difference between the language the Tibetan script was designed for and the language spoken in Lhasa today is not a matter of vocabulary. It is that a distinction once carried in the vocal cords is now carried in the pitch of the voice.

Classical Tibetan had voiced initial consonants: ga, ja, da, ba, dza, zha and za were voiced, and their unvoiced partners were separate sounds. Modern Lhasa speech has devoiced them. What has taken over the job of keeping the words apart is tone. A syllable whose written initial was voiced is spoken on a low tone; one whose initial was voiceless, or which carried certain prefixes and superscripts, is spoken high. The pair that used to differ by voicing now differs by pitch, and no information has been lost, only relocated.

This is why Tibetan spelling repays learning rather than punishing it. The tone of a syllable in the modern language is largely predictable from its written form, including from the silent letters, so a reader who knows the spelling knows how to pitch the word. The relationship runs the other way too: a Tibetan speaker who knows the tone has a clue to the spelling.

Not every variety made the same trade. Amdo dialects retain much of the old consonant system and are correspondingly less tonal, so the neat account above is a description of Lhasa and not of Tibetan as such.