Phonetics Lab., Linguist. Dept., UCLA, Los Angeles CA 90024-1543
Joseph S. Perkell
Melanie L. Matthies
Mario A. Svirsky
MIT, Cambridge, MA 02139
In West African languages, /kp/, /gb/ are described as plosives with simultaneous bilabial and velar closures. From auditory and acoustic evidence Maddieson and Ladefoged (1989) argued that the two articulations are slightly offset in time, with the velar leading the labial. This claim has now been directly tested. Two Ewe speakers provided data using the EMMA system (Perkell et al., 1992). Temporal asymmetry of the two articulations was found, as well as broad similarities to gestures in simple velar and labial stops. In labial velars there is more backward movement of the tongue dorsum than in plain velars; in particular, the tongue back retracts during the closed phase of the stop before releasing forwards. This retraction might result from (a) movements to create suction in the front cavity, (b) increased air pressure in the front cavity pushing the tongue backwards, (c) greater fortition of the velar contact resulting in more compression and displacement of the tongue, or (d) larynx lowering, creating suction in the pharyngeal cavity and pulling the tongue dorsum backwards. Comparison between labial velars and plain velars with respect to the height reached by the tongue back, coordination between movements of the tongue front and back, and voicing features in the acoustic signal suggest that, in these data, pharyngeal cavity expansion is the most likely explanation for retraction.