In Search of Ethnic Cues: The Status of /ae/ and /epsilon/ and Their Implications for Linguistic Profiling

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Title: In Search of Ethnic Cues: The Status of /ae/ and /epsilon/ and Their Implications for Linguistic Profiling
Author: Grimes, Drew
Advisors: Agnes Bolonyai, Committee Member
Walt Wolfram, Committee Member
Erik Thomas, Committee Chair
Abstract: Historically, the study of African American English (AAE), perhaps the most thoroughly documented language variety in the United States, has been centered on syntactic and morphological characteristics. The phonological features that have been discussed are generally limited to consonantal characteristics such as consonant cluster reduction; thorough studies of the vowel systems of African American speakers have only begun to appear in earnest in the literature since the 1990s. Similarly, systematic studies of dialect perception, despite a long tradition in experimental phonetics, have only sporadically been employed in sociolinguistics. This thesis begins to fill both of these gaps by (1) reporting results from two ethnic identification experiments conducted in North Carolina and by (2) reporting data collected from a comparative analysis of two vowels as produced by NC black and white speakers. The vowels examined were /æ/ and /ε/, which are both reported to be raised by African American speakers. The perception experiments required a process of instrumental resynthesis of recorded speech to generate stimuli approximating a continuum of values between two dialectal vowel variants. This process, used for both /æ/ and /ε/, is based on the source-filter theory of vowel production and entails the use of the phonetics software Praat. Using LPC analysis, Praat can synthetically extract a 'filter' from a recorded vowel sound, thereby leaving an approximation of the speaker's unfiltered glottal source. This 'filter' can then be manipulated to represent different formant values and used to refilter the previously generated source signal. With this procedure, a range of experimental stimuli were created for /æ/ and /ε/, representing a continuum of vowels between the black and white variants for each. Results from experimental subjects who heard the stimuli demonstrate that for both /æ/ and /ε/, there was a significant correlation between vowel height and ethnic identification: the stimuli representing a higher vowel position were perceived more often to have been produced by an African American speaker than the stimuli representing a lower vowel position. Furthermore, this correlation seems to be stronger for /æ/ than for /ε/. The data generated by the production study corroborate these perception results. In the production study, F₁ measurements were taken from African American (AA) and European American (EA) pronunciations of the vowels /æ/ and /ε/. These measurements came from field recordings of North Carolina speakers from the North Carolina Language and Life Project archives. The results from this study show a statistically significant difference in the mean AA height and the mean EA height for both of these vowels; furthermore, the difference between the two means for /æ/ was much greater than the difference for /ε/. The impetus for this ethnic identification approach to the analysis of dialect perception comes from the reality of linguistic profiling. Potential landlords and other real estate professionals use this type of racial discrimination to deny housing opportunities to minorities inquiring over the telephone about property availability. The use of such practices is a documented reality; however, many people reject the notion that speakers' ethnicities can be identified based only on their voices. It is hoped that the empirically generated perception data presented here will provide incontestable evidence for the plausibility of linguistically based discrimination practices, and thereby help to solidify the case for legal defendants who have experienced this type of discrimination.
Date: 2005-04-25
Degree: MA
Discipline: English

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