Coarticulation strategies: preliminary implications of a detailed analysis of lower lip protrusion movements

Abstract A two-part experiment on protrusion movements of the lower lip for the vowel /u/ was conducted to investigate: (1) the production of ‘troughs’, i.e., diminution of lip protrusion during the intervocalic consonant in /uCu/ utterances, and (2) ‘time locking’, that is, movement onset at a fixed interval prior to onset of voicing of /u/, regardless of the number of ‘neutral’ consonants in /V unrounded C n u/ utterances. Two speakers of French, a speaker of Spanish and two speakers of English produced similar sets of nonsense utterances. A bite block was used to eliminate mandible movements as a source of lower lip movements. A detailed examination was made of relationships among events in movement and acoustic signals for each token of multiple repetitions of the test utterances. Results suggest that the production of troughs may be due in part to specific articulatory targets for the intervocalic consonants /s/ and /t/. Specific consonantal targets prevented the direct investigation of time-locking. Experimental limitations preclude firm conclusions, but the nature of the results suggests that a complex of factors, including “co-production of adjacent segments” and “context-dependent adjustments of articulatory targets” may underlie observed variation in articulatory behaviour.