I live in Upstate NY, so this is interesting to me! I wonder what our accent sounds like? And WHY did the accents change? I know the same thing happened in England centuries ago, maybe because of population movement after the Black Death.
Although it doesn’t bear on accent, here is an amusing story. In 1988, I read the book “Looking Backwards” by ??? Bellamy. In brief, the idea was that a man from 1888 had somehow been transported to the year 2000 and was looking back to 1888 and describing how life was different. I no longer recall much of the story (except that as prediction it was lousy), but what struck me was the incongruity of people supposedly living in 2000, but using language from the 19th century and then I realized how much language had changed in just 100 years. I hear myself using expressions all the time that didn’t exist in 1937 when I was born. More telling is that I sometimes have trouble understanding my children, so I assume something is changing about the phonetics.
A couple of things that seem to be increasingly common over the past several years that I’ve thought about as changing the language …
People who pronounce “M” not with closed lips but with the top teeth against the bottom lip, top lip pulled high to expose the teeth … I’d guess it is television related.
People, seems mostly teens and twenties, who pronounce words ending in “T” not with the tongue against the front of the palate / back of the top teeth, but with a sort of ‘stop’ at the back of the throat (gutteral stop?). No idea how that one has come about.
I saw a tv programme that mentioned that Rank Odeon( British film production company)actually had an elocution school where the actors were taught the "Hev"for have etc. though whether or not that was a genuine reflection of the middle class accent of the time or some sort of idealised version I dont know.
Found it quite comical in some old films where the rustic milkmaid is speaking in carefully ennuciated middle class tones.