Dialect variation in formant dynamics: The acoustics of lateral and vowel sequences in Manchester and Liverpool English

Abstract

This study analyses the time-varying acoustics of laterals and their adjacent vowels in Manchester and Liverpool English. Generalized additive mixed-models (GAMMs) are used for quantifying time-varying formant data, which allows the modelling of non-linearities in acoustic time series while simultaneously modelling speaker and word level variability in the data. These models are compared to single time-point analyses of lateral and vowel targets in order to determine what analysing formant dynamics can tell 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. These findings are further discussed in terms of hypotheses about positional and sociophonetic variation. In doing so, the utility of GAMMs for analysing time-varying multi-segmental acoustic signals is demonstrated, and the significance of the results for accounts of English lateral typology is highlighted.