Kirkham, Sam and Nance, Claire and Littlewood, Bethany and Lightfoot, Kate and Groarke, Eve (2019) Dialect variation in formant dynamics : The acoustics of lateral and vowel sequences in Manchester and Liverpool English. Journal of the Acoustical Society of America, 145 (784). 784–794. ISSN 0001-4966
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Abstract
This study analyses the time-varying acoustics of laterals and their adjacent vowels in Manchester and Liverpool English. We use Generalized Additive Mixed-Models (GAMMs) for quantifying time-varying formant data, which allows us to model non-linearities in acoustic time series while simultaneously modelling speaker and word level variability in the data. We compare these models to single time-point analyses of lateral and vowel targets in order to determine what analysing formant dynamics can tell us about dialect variation in speech acoustics. The results show that lateral targets exhibit robust differences between some positional contexts and also between dialects, with smaller differences present in vowel targets. The time-varying analysis shows that dialect differences frequently occur globally across the lateral and adjacent vowels. These results suggest a complex relationship between lateral and vowel targets and their coarticulatory dynamics, which problematizes straightforward claims about the realization of laterals and their adjacent vowels. We further discuss these findings in terms of hypotheses about positional and sociophonetic variation. In doing so, we demonstrate the utility of GAMMs for analysing time-varying multi-segmental acoustic signals, and highlight the significance of our results for accounts of English lateral typology.