ॐ · the syllable

Three sounds and a silence. A at the back of an open throat, U rolling forward as the lips round, M closing them — the whole apparatus of speech traversed once, from open to shut — and then turīya, the fourth, which is not a sound.

The mouth as the instrument, which is this app's standing thesis. Sefer Yetzirah 2:3 sorts the twenty-two Hebrew letters by where in the mouth they are made; OM is the same insight compressed into one syllable — the entire mouth, traversed, and then stopped. Both traditions think the body of speech is where cosmology is legible.