I turn to the paṇḍitapariṣad to educate me in what look like technical terms from the science of music. Curiously, in the Yājñavalkya Smṛti (3.112–116) there is a passage about how a person proficient in music and singing can attain the highest Brahman. Why this passage is there to begin with is obscure to me. But at verse 113 we have the mention of seven “gītikāni”: Aparāntaka, Ullopya, Madraka, Prakarī, Auveṇaka, Sarobindu, and Uttara

Then at 114 it says that these should be sung (probably some kinds of chants: Ṛg, Gāthā, (or Ṛggāthā) Pāṇikā, Dakṣavihitā, and Brahmagītikā.

Viśvarūpa has this comment: imāny aparāntakādīni . . . sapta gītikāni gānaśāstrād evāvaseyāni. A hint as to where these come from, but not helpful beyond that.

Aparārka, a bit more helpfully: aparāntikādayo bhārataśāstroktā gītaprakāraviśeṣā brahmajñānābhyāsahetor geyāḥ.

Thank you all for any leads or explanations on this.

Patrick