Despite mass communications, compulsory education, and increasing mobility, American dialects are diverging:
There are multiple examples of such divergence. But none is as dramatic, as baffling to linguists, and as mysteriously under the collective radar as what’s happening in the cities that ring the Great Lakes. From Syracuse, N.Y., in the east to Milwaukee in the west, 34 million Americans are revolutionizing the sound of English. Linguists first noted aspects of the change in the late 1960s. In 1972, three linguists, led by William Labov of the University of Pennsylvania, christened the phenomenon the Northern Cities Vowel Shift or, more simply, the Northern Cities Shift (NCS). What they observed may be the most important change in English pronunciation in centuries.
Some linguists believe that the NCS began with a simple change to the short a sound. When using words with that sound, speakers in the region began moving their tongues forward and up. This “tensing,” as linguists call it, produces a nasal-like sound that is the hallmark of the NCS dialect. Many speakers tense their short a so much that monosyllabic words like cat nearly take on a second syllable. The a sound begins to resemble the word yeah or the final two syllables of the word idea. “If that were the end of it,” Labov explains, “it wouldn’t be a problem, but a language is a set of connected items.” And so, he says, all the vowel sounds start to move around in “something like a game of musical chairs.”
This is called a chain shift, and it stems from a fundamental problem with short vowel sounds: Too many of them occupy too little phonological space, so they constantly jostle to defend their linguistic turf. As a result, a change in one vowel sound can force the rotation of some — or even all — of the others. That’s exactly what’s happening in the northern cities — with a twist. There’s a phenomenon in North American English that linguists refer to as the cot-caught merger. In some North American dialect regions — including Boston, the Western United States, and Canada — the two vowel phonemes in these and similar words are pronounced identically. But the Inland North dialect region, which includes the northern cities, maintains a distinction between them. Caught preserves a wha sound that differs noticeably from the short o of cot. And why not? Distancing the short o in cot from the wha of caught gives many English dialects an extra short vowel sound.
In the NCS region, that extra vowel sound is an integral part of the big shift. The tensing of the short a starts a domino effect. First, the short o rotates into the newly created short-a void. People in Detroit have a jab, not a job. (Or don’t have one, as the case these days may sadly be.) NCS speakers then slide the wha sound into the slot formerly occupied by short o. They now pronounce caught like people from Boston do, but they pronounce cot the way other people say cat. One link down the chain, but tilts toward bought, and further down the short e in words like bet starts to sound like but. The final link in this chain may be the short i of bit elbowing its way in the direction of bet, though its course isn’t entirely clear just yet.