I like to listen to Kojak to hear how New Yorkers used to talk. I used to think they were cool.
My grandmother was not only interested in different accents, but quite like the Henry Higgins character in My Fair Lady, who was able to tell just WHERE someone was from ( in N.Y.C. ), when they spoke.
She told me that NYC accents vary from borough to borough, neighborhood to neighborhood, and in some cases, change withing an area of a block or three.
And I learned a LOT from her and am still VERY interested in all kinds of accents, from everywhere.
Also, there has always been a generational change in the way people pronounce words.
Alistair Cook wrote many books, one of which has a very large section on the different accents in America and WHY they can be SO very different! He said that it was due to WHERE the original settlers came from in the UK. He was 100% correct!
One sort of NYC accent, where "TH" ( thirty =Turty, third=TOID,for example ) was due to the Irish immigrants' pronunciation. Some people in Ireland, TODAY, still have that same way of speaking!