Tibetan Ya ཡ

Ya is the twenty-fourth of the thirty consonants and writes a palatal approximant, the y of English yes. It is also one of the four subscripts, where it is called the ya btags and is written beneath a root letter.

Subjoined ya does not add a glide to the letter above it. It changes that letter. In modern Lhasa speech the labials carrying a ya subscript are pronounced as palatals, so a stack of pa with a subjoined ya comes out with an initial closer to ch, and the sequence a learner would expect to hear is simply not produced.

This is the clearest case in the script of the written stack and the spoken syllable parting company, and it is a rule rather than an exception: it applies across the labials consistently, and a reader who knows it can predict the pronunciation of every stack of that shape.

Ya as a plain root letter carries high tone in modern Lhasa speech. As a subscript it takes no tone of its own, since tone belongs to the syllable rather than to any one of its written parts, which is another reason the stack has to be read whole.

As a root letter ya takes superscripts. It is not a prefix, not a suffix and not a superscript, so of the four subscripts it has the narrowest range: ra and la belong to every stacking system there is, while ya works in one position beyond the root and no more.

A Tibetan syllable is written as an assembly and spoken as a unit, and the relationship between the two is regular without being transparent.

Several of the written parts are not pronounced at all. A prefix is silent. A superscript is silent. A subjoined wa is generally inaudible. What those silent parts do instead is determine the tone of the syllable, so they are not decorative and they are not merely historical: they are still carrying information, in a different medium from the one they were built for.

Other parts change something other than themselves. A subjoined ya palatalises the letter above it. A subjoined ra alters the consonant above it rather than sounding as an r. A suffix reshapes the vowel in front of it. In each case the written element and the spoken effect are in different places.

The result is a script that cannot be read by substitution but can be read by rule, and the rules are neither numerous nor arbitrary. That is the honest description, and it is worth setting against two easy misreadings. Tibetan spelling is not chaotic, and Tibetan spelling is not phonetic. It is a system in which the written syllable predicts the spoken one, given the rules, and does not resemble it.