To use a common American expression, that would be opening a whole can of worms--meaning an extremely complex situation. In each region of the United States, there will be differences in pronunciation, as well as means of expressing emphasis. Click here to visit a thread in which people, mostly Americans, discuss how they pronounce the same words differently.
On the last few pages, for example, people discuss how they pronounce the word sandwich. One member states:
As for sandwich…we in New Jersey definitely say sangwich or sangwitch.
Nobody here in New Jersey (‘cepting me) ever pronounces the “p” in raspberry.
To which another member who grew up in New Jersey responds:
Where in Jersey are you from, or are currently living?
I'm grew up across the river from Pt. Pleasant, in Brielle. We said sandwich or samwich like Boida, and said the "p" in raspberry.
"Boida" refers to a member named Roberta, whose name is pronounced "Raboida" in New York City and parts of New Jersey.
There are people from Maine (far northeast) whose speech is almost incomprehensible to Southerners, and a good many other Americans. There are people from the coastal regions of the Carolinas and Georgia (the far southeast) whose speech is incomprehensible to most other Americans, including other Southerners. Even within regions, certain vocabulary and pronunciations are unique to particular districts.
There are some broad generalities--most southerners say IN-surance, while most Northerners say in-SUR-ance. By and large, though, there are hundreds of regional dialects, with both subtle and gross distinctions from other dialects, and that includes pronunciations intended for emphasis. People from rural parts of the state of Louisiana (the southwestern part of the Old South) will emphasize the word guarantee by saying "I gare-ON-tee ya . . ." People in other regions would say: "I gare-un-damn-tee ya . . . " It would be a lifetime's work just to catalog all the particular dialects.