Linguistics Department, The University of Georgia, Athens, Georgia 30602, USA.
J Acoust Soc Am. 2020 Jan;147(1):579. doi: 10.1121/10.0000549.
Regional variation in American English speech is often described in terms of shifts, indicating which vowel sounds are converging or diverging. In the U.S. South, the Southern vowel shift (SVS) and African American vowel shift (AAVS) affect not only vowels' relative positions but also their formant dynamics. Static characterizations of shifting, with a single pair of first and second formant values taken near vowels' midpoint, fail to capture this vowel-inherent spectral change, which can indicate dialect-specific diphthongization or monophthongization. Vowel-inherent spectral change is directly modeled to investigate how trajectories of front vowels /i eɪ ɪ ɛ/ differ across social groups in the 64-speaker Digital Archive of Southern Speech. Generalized additive mixed models are used to test the effects of two social factors, sex and ethnicity, on trajectory shape. All vowels studied show significant differences between men, women, African American and European American speakers. Results show strong overlap between the trajectories of /eɪ, ɛ/ particularly among European American women, consistent with the SVS, and greater vowel-inherent raising of /ɪ/ among African American speakers, indicating how that lax vowel is affected by the AAVS. Model predictions of duration additionally indicate that across groups, trajectories become more peripheral as vowel duration increases.
美国英语语音的地域差异通常用移位来描述，说明哪些元音音正在趋同或发散。在美国南部，南方元音移位（SVS）和非裔美国人元音移位（AAVS）不仅影响元音的相对位置，还影响它们的共振峰动态。用单个第一和第二共振峰值对元音的中点附近进行静态移位描述，无法捕捉到这种元音固有的频谱变化，这种变化可以表示特定方言的双元音化或单元音化。直接对元音固有频谱变化进行建模，以研究在 64 位演讲者的南部语音数字档案中，不同社会群体的前元音 /i eɪ ɪ ɛ/ 的轨迹有何不同。广义加性混合模型用于测试两个社会因素（性别和种族）对轨迹形状的影响。所有研究的元音在男性、女性、非裔美国人和欧洲裔美国人之间都存在显著差异。研究结果表明，/eɪ、ɛ/ 的轨迹在欧洲裔美国女性中尤其存在很强的重叠，这与 SVS 一致，而非洲裔美国人中 /ɪ/ 的元音固有升高更为明显，表明这个松弛元音如何受到 AAVS 的影响。模型对时长的预测还表明，在不同群体中，随着元音时长的增加，轨迹变得更加边缘化。
