Articulatory control of phonological vowel length contrasts: kinematic analysis of labial gestures.

The present study investigated the articulatory control of the German vowel quantity contrast, i.e., the phonological difference between short and long vowels. By means of an optoelectronic system the excursions of the compound lower lip/jaw opening and closing gestures were measured during production of test sentences comprising the target sequence /pVp/ (V = /a/, /i/, /u/, /a:/, /i:/, /u:/). First, a highly linear relationship between peak velocity and movement amplitude emerged within each quantity class. Second, vowel quantity systematically influenced the scaling of velocity and amplitude during oral opening. Third, as compared to their short counterparts, long vowels showed an increased peakedness of the velocity profile. Finally, the velocity profiles of the long vowels were characterized by an asymmetric shape in terms of a prolonged deceleration phase of the opening and a lengthened acceleration interval of the closing movement. With respect to durational coarticulation patterns, the control of vowel quantity clearly differed from intrinsic, i.e., vowel type-induced, variability. The latter was partially compensated for the level of word duration by shortening of the prevocalic consonant whereas vowel quantity turned out to be primarily due to the lengthening of the syllable /pV/.