One segment of last night’s PBS broadcast on American English particularly struck me: the one devoted to the Northern Cities Vowel Shift, prominent in cities like Chicago, Detroit, Cleveland, and Buffalo (surprisingly, it seems to be spreading in St. Louis). You can get a description (with chart) here (scroll down to “The Northern Cities Shift”) and hear samples here; it’s one thing to read about it, but you haven’t lived until you’ve heard a recording of someone saying (what clearly sounds like) “boss” and discovered that what she was actually saying was “bus.” According to the Wikipedia article:
The shift is more notable in Caucasian speakers and those who identify themselves with the region in which the vowel shift is occurring. Speakers of African American Vernacular English show little to no evidence of adopting the Northern Cities Shift. The NCS also is not being used by Canadian speakers despite the geographic proximity of speakers in the United States and Canada about the Great Lakes region.