Speech and Lang. Pathol., Dept. of Commun. Sci. and Disord., Northwestern Univ., 2299 Sheridan Rd., Evanston, IL 60208-3570
This study investigates the acoustic correlates for the four manners of stop articulation ([(plus or minus)voice, (plus or minus)aspirated]) at the four different places of articulation (labial, dental, alveolar, and velar) in Urdu. The study follows up Davis' work [J. Phonet. 22, 177--193 (1994)] on manner in the homologous velar stops in Hindi. Data from four subjects for the 16 stops (ten different tokens of each stop for each subject) support Davis' assertion that F2 ``lag'' time (between stop-released and onset of F2 for the following vowel) is a more conclusive measure for the feature [aspirated] than the traditional voice onset time (VOT) measure. However in Urdu, unlike Hindi, lag time alone does not exhibit a four-way contrast. A measure of ``lead'' time (pre-stop-release voicing) is also required. Thresholds for lead time and lag time permit all four manners to be distinguished without reference to the place of articulation for all the subjects. Thus the phonological features [voice] and [aspirated] are more phonetically orthogonal in Urdu than Hindi. The results contribute to the ongoing debate on the invariance versus variability of acoustic cues, and to the discussion concerning the representations relating the phonological and phonetic levels of speech.