Articulatory strategy as a source of variation in acoustic vowel dynamics
For speech scientists, this provides empirical evidence linking articulatory strategies to acoustic variation, illuminating the sources of speaker individuality.
The study demonstrates that distinct articulatory strategies for producing the vowel /i/ significantly predict formant dynamics in diphthongs with a palatal offglide, based on ultrasound data from 36 speakers. Greater articulatory displacement leads to earlier and steeper formant transitions.
Acoustic vowel dynamics have some speaker-identifying characteristics, which have been ascribed to individual properties of articulatory strategies: formant transitions have a particular shape because speakers move their articulators, using specific and practised movements. However, there is little existing evidence that different articulatory strategies systematically affect formant dynamics. The present study corroborates the link between the two. Ultrasound tongue imaging data from 36 speakers of Northern-Anglo English are used to identify distinct articulatory strategies for the production of palatal vowel /i/. Tongue shape in /i/ is found to be a significant predictor of formant dynamics in diphthongs with a palatal offglide. The observed relationships can be explained by the characteristics of articulatory movement conditioned by vocal tract shape. Greater articulatory displacement of tongue root and/or dorsum produces greater distortion from the mean tongue shape in palatal vowels, and it also requires higher articulatory velocities, resulting in relatively earlier and steeper formant transitions. The results contribute to the conceptual understanding of individuality in speech, by illuminating the regularising and individual aspects of articulatory compensation.