Anders Lofqvist
Vincent L. Gracco
Haskins Labs., 270 Crown St., New Haven, CT 06511-6695
Studies applying mechanical perturbations to the lower lip and the jaw have shown a trade off between movements of perturbed and unperturbed articulators in making the lip closure for a bilabial stop. While this concept is attractive, evidence for such trading relationships in normal speech has remained elusive, partly due to methodological problems. This study examines the vertical positions of the upper and lower lip at closure for bilabial stops. An electromagnetic transduction system was used to track receivers on the upper and lower lips, and the lower incisors for transducing jaw movements. The speech material consisted of VCV sequences where the first vowel was /a/, the middle consonant /p,b/, and the second vowel /i,a/; stress occurred on the second vowel. Preliminary results from three subjects showed upper lip positions at closure to occur over a range of 0.3 cm; the range for lower lip positions was 0.5 cm. Examination of 40 tokens for each subject revealed a positive relationship between upper and lower lip positions at closure, with correlation coefficients ranging from 0.5 to 0.7. The results will be discussed in relation to theories of speech motor control. [Work supported by NIH.]