Mongolian Kha and Writing a Distinction You Cannot Hear

Adding a letter for a sound your language does not use raises a question that every transcription system has to answer: who is the letter for? A Mongolian reader with no Sanskrit will not pronounce an aspirated velar differently from a plain one, and for that reader the letter carries no sound at all. It carries spelling rather than pronunciation, which is a real and useful function. It preserves the shape of the source word, so that a term can be traced back, compared with its Tibetan or Sanskrit original, and distinguished from another term that would otherwise look identical.

Learned traditions across Buddhist Asia have made the same choice, and Japanese and Chinese Buddhist writing both preserve distinctions in the spelling of transcribed terms that ordinary speakers do not produce. The alternative is what happens to loanwords in daily speech, where the sounds of the receiving language take over completely and the origin becomes invisible within a generation or two. Mongolian Buddhist writing chose the learned route for its technical vocabulary and the ordinary route for everything else, which is why the added letters cluster in religious and administrative texts and are rare elsewhere.