THE INTEGRATION OF COARTICULATED SEGMENTS IN VISUAL SPEECH

The perception of phones in visible speech is affected by coarticulation. In this study, visual speech stimuli are created by concatenating an image of the articulatory target position of the vowels /i:,a:,u: / with an image of the target position of the consonants /p,�,k/. These phones differ in their labial articulations: /u: / is the only rounded vowel, the close articulation of /i: / is compatible with rounding, while the open articulation for /a: / is not; /p / is a labial consonant, /� � has secondary labialization and /k / only acquires coarticulatory rounding in the context of a rounded vowel. In this paper, the different effects of the consonant articulation on vowel perception are investigated, and vice versa. Differences between the phones in susceptibility to coarticulatory effects are confirmed, and it is shown that in the stimuli used here the perception of a phone is affected by its neighbor, particularly the rounding in an /u:k/ sequence can be interpreted as labiality of the consonant. Even if there is no coarticulatory rounding in /k/, because it was taken from an /i: / or /a: / context, the rounding of /u: / can lead to the perception of labiality in the following consonant. Vice versa, the vowel /i: / can be perceived as /u:/ when followed by a /k / taken from an /u: / context; for /a:/, this is less often the case. This shows that the labial articulation can be reinterpreted as a property of the neighboring phone (if it is compatible with its other articulatory properties), not just of the phone on which it appears. 1