Sanskrit

[Bodhi]

great explanation Ashok Ji. To your point, see what a couple of such scientists of our past (Bharata and Abhinavagupta) say upon the topic of vibhraShTa (corrupted) pronunciations. And they are not criticising but only differenciating such pronunciations from the pure and classical saMskR^ita:

(cross posting a small subset from here)

such words in which the <b>combined vowels or consonants change or cease to exist are called vibhras.t.a (corrupted)</b>. In Prakrit there do not exist ai after e and au after o and the visarga h after the anusva_ra am. Also there do not exist s’ and s. in between va and sa as also ng n~ na the nasals which occur respectively at the ends of ka ca ta varga-s. [In other words <b>the eight syllables ai, au, h, s’a, s.a, ng, n~ and na do not occur in Prakrit. Abhinavagupta adds four additional syllables which do not in Prakrit: r.r., l and l.</b>] (18.8)

The subsequent verses are similar explanations of letters which occur in Prakrit such as ka, ga, ta, da, ya and va which are slightly audible; examples of cakra becoming cakka, occurrence of ha in place of five letters: kha, gha, tha, dha and bha as in: mukha = muha, megha = meha; katha_ = kaha_; the change of letter s.a into ccha as in s.at.pada (cchappao); the change of dha into d.ha (vardhana = vad.d.han.a). The elucidation and examples provided in 18.9 to18.27 are remarkable and impressive list of evidences of changes in word forms in Prakrit compared to Sanskrit.

Abhinavagupta adds a comment that Bharata has only given an indication. Those who want a detailed account should consult books like Prakritadipika. (The identity of this work has yet to be established).