Try to pronounce the words "caught" and "cot." If you're a New Yorker by birth, the two words will sound as different as their spellings. But if you grew up in California, you probably pronounce them identically.
American English is slowly changing; across the nation, the two "low-back" vowel sounds in these words are merging, region by region. Now Christina Esposito of the Macalester College has tracked the change sweeping eastwards across the Midwest into Minnesota. She will present her findings at a meeting of the Acoustical Society of America (ASA) next week in San Antonio, TX.
Working with graduate students Hannah Kinney and Kaitlyn Arctander, she asked Minnesotans to read a list of 100 words that contain these vowels, recorded the speech, and analyzed patterns within the recordings.
"We make a visual representation of the speech, a spectrogram," says Esposito. "Every single vowel has its own unique frequencies, like a fingerprint."
Unlike past studies of other areas of the country, which rely interviewing people over the telephone and judging differences by ear, Esposito's experiment recorded and dissected the speech quantitatively. Her results suggest that 30 percent of Minnesotans have lost the distinction between the two vowel sounds.
More information: The talk "Low-back vowel merger in Minnesotan English" (1aSC4) by Christina Esposito is on Monday, October 26. Abstract: asa.aip.org/web2/asa/abstracts/search.oct09/asa37.html
Source: American Institute of Physics
Explore further: US: NYU researchers took bribes from Chinese group