Inst. de la Communication Parlee CNRS No. 368, Stendhal, BP 25, 38040 Grenoble, France
Jaw vertical position of VCC vs VVC quantity contrasts in Arabic uttered at two speech rates were monitored. Events detected are: jaw lowering onset (VCO), and maximum velocity (MVV), jaw raising onset (CCO), and maximum velocity (MCV). Results show that at conversational rate, contrasts depend on differences in absolute timing along only one cycle (VCO--VCO). At fast rate, relative timing values no longer carry quantity contrasts for two speakers (out of four) within this cycle, whereas the contrast is still maintained in the MVV--MVV cycle. Velocity profiles for the raising gesture show that speakers who lose contrasts in relative timing in the VCO--VCO cycle, are also speakers who lose them within this gesture at fast rate: in fact, they lose the absolute lead that geminates have over nongeminates in the acceleration phase of this gesture. Consequently, it appears that contrasts rely mainly on the timing of raising gestures that follow the vowel, thus hiding it faster when the consonant is a long one.