Phonology is the study of the (abstract) sound systems underlying the physical (articulatory and acoustic) aspects of speech. Phonology plays a central role in Pāṇini’s Aṣṭādhyāyī, which derives precise pronunciations from more abstract underlying representations. Alongside the tradition of Vyākaraṇa, the Prātiśākhyas, part of the Śikṣā tradition, display a similar, and perhaps slightly earlier, trend of phonological analysis.
After the early period, phonological analysis as such does not play a major role in the Indian tradition, being taken as largely established. However, important principles of grammatical theorizing, such as theories of rule interaction, which depend in significant part on the phonological analysis of Pāṇini and the earlier tradition, remain a topic of debate (see Lowe 2021).