When Vivien Leigh was preparing for her classic role as Scarlett O'Hara in the movie "Gone with the Wind," she worked hard to develop an accent that would evoke the languid, plantation life of the antebellum South. There was just one problem. Southerners didn't talk that way in Civil War days. Thanks to recently discovered audio recordings of interviews with Civil War veterans and former slaves made more than 45 years ago, there's evidence that what we might consider the archetypal southern accent didn't appear until after 1880, says Guy Bailey, dean of liberal arts at the University of Nevada at Las Vegas. {Soundbite: 5462.} While the pre-Civil War habit of not pronouncing the "r" after vowels survived, two changes occurred to help form the 20th-century Southern accent: Pronunciation of certain vowels shifted, and a drawl was introduced that made one-syllable words sound like two syllables. {Soundbite: 5460.} Pronunciation of words such as "bait" became "bay-uht," and "bid" became "bee-uhd." "Bed" turned into "bay-uhd," and die became "dah." Before 1880, southerners also pronounced "er" as "oy," as in "I saw the boyd' {bird} fly from the boych' {birch} tree." That pronunciation today is heard in isolated areas of the South and is related to the classic "Toyty-Toyd {Thirty-Third} street" pronunciation heard occasionally in New York City. "Language change can be predicted about as easily as earthquakes," says Alan Metcalf, executive secretary of the American Dialect Society. And like the continents, pronunciation is shifting constantly, although at a faster rate. Vowel pronunciation is a major component of those changes. The most significant vowel shift in the history of spoken English happened from 1400 to 1700, according to Joel Davis, in his book Mother Tongue. This change is one thing that makes it difficult to understand the poet Geoffrey Chaucer, who wrote Canterbury Tales and died just before the shift began. For example, in Chaucer's time, the "a" in "fame" sounded like the modern pronunciation of "a" in "father," making the word sound more like "fahm." The "e" in "see" sounded like the "a" in the modern "same," so "sea" became "say." The letter "o" was long, making "to" sound like today's "toe." "Lyf" (life) was pronounced "leaf." And, in Chaucer's time, people usually pronounced the final "e" in words such as "stone," "have" and "love." Here is a passage from Chaucer's "The Wife of Bath's Prologue:" "Now, sire, now wol I telle forth my tale. / As evere moote I drynken wyn or ale, / I shal seye sooth; tho housbondes that i hadde, / As thre of hem were goode, and two were badde." Here is how it would have been pronounced, according to Daniel Donoghue of Harvard University: Noo, seer, noo wol ee tell fawrth mee talle / as ever moat ee drincan {short i as in tin'} ween or alle, / ee shall sigh soath; tho hoosbonds that ee hadde, / as thray of hem wear goade, and twoa {pronounce the w} wear badde. Even today, vowels continue to shift in the United States. "In spite of the fact that we watch the same TV programs and listen to the same radio programs, the accents of the major American cities are getting more and more different from each other," says William Labov, a linguistics expert at the University of Pennsylvania. "It's an astonishing fact." For example, Labov has been researching a major vowel shift that has accelerated in recent decades in northern American cities, particularly among the white lower-middle class in the Great Lakes region. This shift is marked, for example, by pronunciation of the short "a" as "ee-a," so "Ann" sounds closer to the name "Ian" and "bag" sounds somewhat like "bee-ag." The short "o" is moving toward a short "a," so "sock" sounds closer to "sack." {Soundbite: 5464.} Spreading throughout a larger area of the United States are vowel mergers, in which pairs of words gain the same pronunciation, such as "Don" and "dawn," both pronounced "dahn." In most of the South, "pen," pronounced "pehn" in other places, sounds like "pin" ("pihn"). Another major pronunciation shift in the United States involved "r." Before World War II, it was a mark of prestige among the upper economic classes in areas such as New York City not to pronounce the "r" after vowels in words such as "barn" or "card." But after World War II, the working class started dropping the "r," and the upper classes now often pronounce the consonant. In parts of the South, such as Raleigh, the older aristocracy and the working classes continue their tradition of leaving out the "r," while younger, wealthier people are pronouncing it, says linguist Walt Wolfram. Although some pronunciations are associated with certain socioeconomic groups, accents in America say less about one's social standing than in Great Britain. There the "received pronunciation," associated with Oxford and Cambridge universities, is a dead giveaway about upper-class roots. Yet status issues involving pronunciation do exist in America. At the University of Georgia in Athens, linguist Bill Kretzschmar has found students concerned about their thick Southern accents, even though they attend school in the heart of the South. "One student said, I hope you won't give me a bad grade because of the way I talk,' " Kretz-schmar recalls. Bailey says that he comes from a "poor, working-class, southern Alabama family" and that, to succeed in the broader world of academia, he had to tone down his regional accent occasionally. To be understood in Nevada, where he lives, he still must be careful how he speaks to strangers, he says. For example, he makes an effort to say his name, Guy, with the more widely recognized pronunciation "Geye," not his Alabama-inflected "Gah." When talking to the operator, he says the number "nine" in the non-Southern way ("nah-een") not "nahn." "There are certain times you need people to focus on what you're saying and not how you're saying it," Bailey says. All across the country, professionals tend to downplay their accents if they are working outside their region of origin. But that is not always the case. In some places, regional accents are emphasized as a mark of social identity. In the late 1980s, for example, Bailey surveyed native speakers of Texas and found to his surprise that use of a typical Texas accent was expanding among all socioeconomic groups. Survey participants were asked to say the word "night" and then asked how they felt about Texas. Those who said "naht" in the traditional Texas way tended to view the state as great place to live. Now, people "are proud to be native Texans," he says. Accent also reflects a strong sense of cultural identity among white teenagers from suburban Detroit, who were studied by Penelope Eckert, a linguist at Stanford University. "Burnouts," who are from working-class roots and not college bound, tend to wear their accent as a badge of cultural identity, separating them from the college-bound kids known as "jocks" in the same school, Eckert says. The burnouts' neighborhood-oriented accent includes much of the Northern vowel shift, particularly for words such as "lunch" (pronounced "lawnch") or "flesh" (pronounced "flush"), because of the youths' strong local orientation. The jocks, bound for lives beyond their neighborhoods, have a less regionally marked speech.

CAPTION: Clark Gable and Vivien Leigh in the 1939 movie "Gone With The Wind."