Analysis of total vowel space areas in three regional dialects of American English

The acoustic characteristics of vowel systems in different varieties of American English are greatly affected by regional variation. Given the significant positional differences of vowels within the acoustic space across regional dialects of English, one should expect that the size and extent of the vowel space is also affected by this type of variation. Traditionally, the size of the acoustic vowel space has been measured as the triangular area defined by the three corner vowels. An obvious weakness of this approach is that it underestimates the actual "working space" of vowel system in that the onsets and/or offsets of other vowels are often found outside this triangular area. This paper proposes a procedure to estimate the area of a complete vowel space, taking into account dynamic formant pattern of all vowels and diphthongs. Complete vowel space areas are calculated for individual speakers and compared across three distinct regional varieties (representing Inland North, Southern Appalachian, and a Midland variety). The comparison also examines possible changes to vowel space area as a function of speaker generation (younger and older adults).