Interarticulator programming: effects of closure duration on lip and tongue coordination in Japanese

This paper examines the coordination of lip and tongue movements in sequences of vowel-bilabial consonant-vowel where the duration of the oral closure for the consonant is varied for linguistic purposes. Native speakers of Japanese served as subjects. The linguistic material consisted of Japanese word pairs that only differed in the duration of the labial consonant, which was either long or short. Recordings were made of lip and tongue movements using a magnetometer system. Results show a robust difference in closure duration between the long and short consonants. The tongue movement from the first to the second vowel had a longer duration in the long than in the short consonants, and its average speed was slower in the long consonant. The size of the tongue movement path between the vowels did not consistently differ between the long and short consonants. The tongue movement almost always started before the oral closure for the consonant, while the onset of the lip movement towards oral closure mostly started before that of the tongue movement. The offset of the tongue movement occurred after the release of the closure, but there was no clear pattern for the long and short consonants.