What I learned growing up was that words with the pinyin “er”, like 儿, 二, and 耳 were pronounced [ɚ], but younger/more native speakers of Standard Chinese seem to pronounce it as [aɚ], and I was wondering if I should switch my pronunciation over to that.
Wikipedia’s page on erhua has some nice information on these “non-erhua r-colored syllables” but is still a bit vague about exactly which type of people are using which pronunciations:
All of the non-erhua r-colored syllables have no initial consonant, and are traditionally pronounced [ɚ] in Beijing dialect and in conservative/old Standard Mandarin varieties. In the recent decades, the vowel in the toned syllable "er" has been lowered in many accents, making the syllable come to approach or acquire a quality like "ar" (i.e. [aɚ̯] with the appropriate tone). In some new accents and some different accents than Beijing, all the non-erhua r-colored syllables (may) use "ar"-like qualities regardless of tones.
So, what are the different connotations of the two pronunciations? How recently did the shift happen? Does [aɚ] make you sound young and [ɚ] make you sound old? Is one pronunciation more prestigious than the other, and the other more casual? Is there a Northern/Southern divide?