[QUOTE=Johanna]
The OP specified ancient Sanskrit as the criterion.
The only pronunciation difference I know of between ancient and modern Sanskrit is ऋ /ṛ/ the vocalic “r” vowel which was pronounced like in “grrr” in ancient Sanskrit but now is pronounced “ri” in Hindi* or “ru” in Kannada. Similarly for ऌ vocalic /l/.
*Back in the 1970s, the days of Don Kirshner’s Rock Concert, people used to tease the Hare Krishnas by saying “Harry Kirshner.” Ironically, in ancient Sanskrit Krishna actually was pronounced like “Kirshner.”
The /t[sup]h[/sup]/ in Siddhartha is dental, not retroflex. Although etymologically, the consonant /r/ did trigger retroflexion in Sanskrit, it didn’t in this name. Your professor mispronounced the /s/ too, was he or she Bengali?
Speaking of etymology: The name सिद्धार्थ siddhārtha is a compound of two Sanskrit words: siddha ‘accomplished, successful’ and artha ‘aim, purpose, cause, motive, reason, advantage, use, utility, thing, object, membrum virile (i.e. penis), object of the senses, wealth, property, opulence, money’, etc. Together they mean ‘one who has accomplished an aim or an object, successful, prosperous’.
Sanskrt grrrl Johanna
[/QUOTE]
If it helps, the name is sanskrit but it’s highly unlikely that he had many contemporaries who would’ve used it. Based on the time period and the areas he allegedly taught in, it’s much more likely that he used Magadhi Prakrit… you might be able to find cheshirisms to this effect in the Pali canon, but I don’t know what the sound changes operating between the three would’ve been.