प्रातिशाख्यम्

तैत्तिरीय-प्रातिशाख्ये “आदिरस्योदात्तसमः शेषो ऽनुदात्तसम इत्याचार्याः॥” इत्य् अवधेयम्। (मूलम् अत्र)। paaNini’s arrangment is explicitly allowed. there is one other similar alternative. The pair that grant higher tone to the first half hrasva duration only are still different from current “pure higher tone” or rising tone practice. Also, some “hand waving” is allowed by the last sUtra (सर्वः प्रवण इत्येके॥१.४७॥).

As shrI dhananjaya says:

“As you can see from the description, when this passage was written, apparently one couldn’t just listen to people speak, and know the pronunciation.”

वाजसेनयि-प्रातिशाख्ये (मूलम् अत्र): “उच्चैरुदात्तः, नीचैरनुदात्तः, उभयवान् स्वरितः” १.११०। एवञ्च - चत्वारस्तिर्यक् स्वरिताः १२२ … तस्यादित उदात्तं स्वरार्धमात्रम् १२६

What about multiple non-pANiniiya options preserved in – say – taittiriiya prAtishAkhya?

As shrI dhananjaya says:

“Thus the complete opposite options given for the second part of the svarita. Either it is the same level as udAtta (1.42), extremely low (1.44), the same as anudAtta (1.45) … Or the first part is like udAtta and the next part is like anudAtta, “according to the teachers”, I.e., pANini-tradition 1.46. By the time this passage was written, it appears that people did not speak this as a first, or nearly-first language. So one basically repeated extremely polar opposite pronunciations. … This does not happen in pANini’s own description. People who travelled to the north and south banks of the VipAsh (उदक् च विपाशः॥ ४।२।७३ – “अञ् प्रत्ययो भवति चातुरर्थिकः। अणो ऽपवादः। … स्वरे विशेषः। महती सूक्ष्मेक्षिका वर्तते सूत्रकारस्य।”) (today’s Beas) river could hear that names of wells were pronounced differently, and pANini’s job was to describe it. … By the time of this prAtishAkhya, this sort of obvious demonstration of sounds was not available in society. This prAtishAkhya is an accurate description of various optional liturgical uses (not for communication, but for worship). For worship, it is presumably the right thing to do whatever one’s own shAkhA prescribes. The aim of worship is personal-spiritual, not communication!”