Well yes I think we can all agree that people from the south tend to talk languidly, and people from Yankee country tend to talk quickly and clipped
It is the clipped part and the drawling dipped i's and o's thst make the difference. It is not really a speed difference at all, just the way the ear perceives it. In the South we tend to leave off the hard endings ("endins"), whereas Northerners are very precise to put them in. We especially differ on "T" and "D". So hearing that "clip" come along at a rapid pace makes it sound like someone is speaking faster than someone who's using rounder tones.
I had to study all this taking voice. They (especially my childhood voice teacher) really don't want you to have any discernible accent when singing, so that it appeals to all people. Until I get tired, most people don't even know I'm from the South - they can't tell where I'm from, I'll get 3 different guesses from 3 different people (unless I use the word y'all in a sentence, LOL!)
But when I start getting tired or have a headache, that drawl starts sneaking in. My husband says he can tell how tired I am by how long my "I"s are getting.
