An Acoustic Phonetic Analysis of African American English: A Comparative Study of Two Dialects

In this thesis, I contribute acoustic phonetic data and analysis to the study of African American English (AAE). For this research, I collected speech samples of self-identified AAE speakers and speakers of a dominant coexisting dialect, the Northern Cities Shift (NCS). I analyze these samples to determine if vowel quality and vowel duration are consistently and predictably varied between the two dialects. Labov's Chain Shift Principles are used as the context for the results. In my analysis, I find that both vowel quality and duration are different between AAE and NCS in ways previously undocumented in the linguistic literature. The quality analysis relies on evidence from the vowel [ ae ]. I find that AAE shares a distinct quality feature of NCS, raised [ ae ], despite the fact that this feature is said not to be present in AAE. This vowel functions as the pivot point for the chain shift in the NCS data but does not cause a vowel shift in AAE data analyzed in this thesis. In the analysis of vowel length, I rely on data from the front tense/lax vowel pairs, [ i ; ] and [ e ; ] in both dialects. I find that vowel ɪ ɛ length is consistently longer in AAE than in NCS. Additionally, I find that in NCS, the tense/lax pairs maintain a difference in length in which the tense vowels are longer than the lax vowels. In AAE, I find that the tense vowels are shorter than the lax vowels. I conclude that the length differences found in these data sets indicate that Labov's feature [ +/peripheral ] is not a feature of the AAE front tense/lax vowel pairs, [ i ; ] and [ e ; ] ɪ ɛ and that this prevents a vowel shift in AAE that should occur in response to the presence of the raised [ ae ].