Examining visible articulatory features in clear and conversational speech

This study investigated the relationship between clear and conversational speech styles and motion of visible articulators. Using state-of-the-art computervision and image processing techniques, we examined front and side view videos of 18 native English speakers’ faces while they recited six English words containing various vowels (keyed, kid, cod, cud, cooed, could) and extracted measurements corresponding to the lip and jaw movements. Significant effects were found for style, gender, and saliency of visual speech cues. Clear speech exhibited longer vowel duration and more vertical lip stretching and jaw movement for all vowels, more horizontal lip stretching for front vowels, and a greater degree of lip protrusion for rounded vowels. Additionally, greater articulatory movements were found for male than female speakers in clear speech. These articulatory movement data demonstrate that speakers modify their speech productions in response to communicative needs in different speech contexts.