The Taittīnya-Āraṇyaka mentions, for the first time, the various constituents of the ancient science of phonetics:
Prap. vii, An. 2.
At the present day no Śikṣā work contemporaneous with the above and comprising all the said parts is to be traced. In general, the Prätiśākhyas and the still later Śikṣās deal at sufficiently great length with traditional Sanskrit phonetics of their own times; but the common source from which Patañali derived most of his quotations, which was afterwards used by Candragomin to form his Varṇa-sūtras, and which has been extensively quoted and reproduced by subsequent commentators of such high repute as Jayāditya, Jinendrabuddhi, the author of Prakriyā-Saṅgraha of the Jain Śākaṭāyana School, Sṣṭridhara and a host of others, was little known till recent times.