Isn't it funny how, in so many countries, when you get to the southern part, people start drawling their words? I know this is true in the southeastern part of Bangladesh, where my parents are from. In Chittagong, people drawl their words, and syllables seem to run together. (Think "y'all".) It's difficult for those used to northern, proper Bengali (the version spoken in Dhaka or Calcutta) to understand.
This accent/drawl phenomenon clearly holds in the U.S., and apparently in Japan (where people speak a "funny" version of Japanese in Osaka, and where the Japanese in southern Kyushu sounds a bit drawled), and China (where Cantonese certainly sounds more drawled and casual than Mandarin). I think Mrs. Octopus told me this is also the case in Vietnam. I don't know about other places. Does this sort of thing happen in France, Germany, Italy, Ethiopia, or Iran? Maybe people just get tired in the heat and can't be bothered with enunciating every last syllable?
Maybe the whole north/south thing is a red herring, and it's mostly about being far from the metropolitan center in the region. For example, London -- home of proper English -- is relatively south in England. It is interesting how accents from different regions in a country come to represent different levels of class and sophistication: "In Germany the Prussians were considered the ruling class, he said, and the eastern German accent was associated with education and style. Then came communism. Today, said Kretzschmar, the East German accent is associated with poverty and backwardness." Atlanta Journal-Constitution.
And then, of course, there are the issues of accents developed among various minority groups (black english, Spanglish, etc.), and the hierarchy of foreign accents (English, French, or German vs. Indian, Chinese, or Mexican). In America, it seems certain foreign accents carry a cachet of sophistication and erudition (the old world accents) versus the stigma of backwardness (others).
I'm holding onto my Connecticut accent as long as I can out here in L.A. before I succumb to saying "dude" and "like, totally" like all the time.