“Most recently, I've been examining the features that have changed or died out, and those that haven't. So, just, very briefly, some of the ones that you don't hear so much anymore are some of the vowel sounds like the 'i' in the past was more likely to be produced as 'oy' so you'd have 'f-oy-t' (fight) and 'l-oy-t' (light) and that still happens some in the younger speakers but not as much.
“And the other one is the '-ow' sound becomes more like 'eeow' so instead of 'cow' you have 'kee-ow', and that has almost completely died out, you only hear that in older, usually farmers because they're still living out in the rural areas and usually men.
“And then the other feature that I study is the glottal stop. It is a sound that is produced in the glottis, which is where the vocal folds come together in the throat and when those vocal folds sort of slam together a little bit, it makes that sound.
“When it replaces another sound like the 't', it becomes more noticeable. So a word like 'Vermont' becomes 'Vermon-', a word like 'mitten' becomes 'mi--en', and a word like 'mountain' becomes 'moun-ain'.
“Speakers who used it most were the high school students. So that indicates that since teenagers tend to be the ones who really create accents and dialects and whatever kind of speech is going to continue into the next generation, when they are doing something a lot it indicates that it's not going away anytime soon."