I cannot tell the difference between scent, sent, cent, they sound the same.
This reminded me of my ex though - his name was Don and down here the boy name Don and the girl name Dawn sound the same. This made him so mad because where he came from (also in the US) they sounded completely different. He pronounced the girl name Dawn almost like "Dwan" and the boy one Dahn, sort of nasally.
So I can believe they sound different in different places but it would not be related to the volume or pitch. Rising pitch at the end of a phrase makes it a question so it has meaning in that way, and some words can change based on which syllable gets the accent - object, content, project as examples.
