1. Conclusions  Constriction Type does influence AV speech perception when it is visibly distinct Constriction is more effective than Articulator in this stimulus context critical constriction degree (fricatives) shows the strongest visual influence  Active Articulator had little visual effect labials did not have greater effect than linguals However, passive articulator differences may account for the strong /v/-/D/ effects  Articulatory Phonology implications for AV speech perception/production research gestural parameters may offer better (or additional) guidance than phonetic features Précis In audio-visual (AV) speech perception the two modalities convey largely complementary information (V: Place, A: Manner). But place can be low visibility, and manner visible. Articulatory Phonology and ecological/direct realist views imply that examining visible vs. audible gestural structure may offer novel insights.Perceptual effects of active articulator vs. constriction degree were examined in a McGurk task using anterior consonants that differ visibly on both dimensions. Visual impact was greatest for incongruent A-V signals that used different articulators but same constriction type, stronger for fricatives than stops/glides, yet failed to yield an articulator effect. Thus, constriction affects AV perception, more so than active articulator, in identification of visually distinct anterior consonants. Background Audio-visual (AV) speech perception shows modality-specific contributions (MacDonald & McGurk, 1978; VPAM : Summerfield, 1987):  Audio provides primarily manner information  Visual provides place of articulation information Yet, some qualifications re: those assumptions:  place and manner imperfectly related to visibility: place (POA) visibility varies labials vs. non-labials also some visibility for some coronals face dynamics re: other POA info (below) manner also varies: stops - fricatives - glides unclear how narrowly to define POA, e.g. /b v/ SAME: labial ( broad transcripttion) DIFFERENT: labiodental vs. bilabial (narrow transcription)  dynamic visual speech information is distributed across the talking face/head (Yehia et al., 1998) correlates with tongue as well as lip and jaw movements this info can guide intelligible audio synthesis Articulatory Phonology (Browman & Goldstein, 1992, 2000) suggests an alternative: A-V perception re: articulatory gestures (cf Fowler & Dekle, 1991)  Active articulator: lower lip vs. tongue tip/blade  Constriction degree: closed - critical - narrow Results: Experiment 1 Ê Gestural Incongruity Type main effect, p <.0001  Visual influence was strongest when A and V tokens differed in Articulator but shared the same Constriction degree Ë Gestural Incongruity x Articulator, p =.0084  The preceding effect was more pronounced when the video token used lips than tongue tip Results cont’d: Experiment 1 ÊConstriction Type main effect, p =.0001  Visual influence on perception was greater for fricatives than stops Ì Gestural Incongruity x Constriction, p <.0001  /v/-/D/ pairs showed the strongest visual effect, followed by video stop paired with opposite- articulator fricative Í Articulator x Constriction, p <.017  Both fricatives had strong visual effects, but labial stop > lingual stop Experiment 2 ÊGestural Incongruity Type main effect, p <.0001  Replicated that of Experiment 1 Î Constriction Type main effect, p =.0001  Again, fricatives had a larger visual effect than stops; in Exp. 2 they also superceded glides Results cont’d: Experiment 2 Ï Gestural Incongruity x Articulator, p <.053  marginal: largest visual effects for /v/-/D/; /b/-/d/ pairs and video fricative + audio stop/glide yielded next largest visual effect Ð Gestural Incongruity x Constriction, p <.0001  Replication/extension of Exp. 1 interaction effect. /v/-/D/ showed strongest effect by far. Video glides with opposite-articulator stop/fricative was next-strongest. AVSP’05 Influences of Visible Place Versus Manner Distinctions on Perception of Audio-Visual English CV Syllables Catherine T. Best & Daniel Lazarek c.best@uws.edu.au Research Question: How do visible distinctions in active articulator and constriction degree contribute to AV speech perception? Method Stimuli anterior Cs (USA English) that differ visibly re: u Active Articulator lower lip tongue tip/blade u Constriction: closed (stop) critical (fricative) narrow (glide) (included only in Exp. 2) Subjects English (USA) : Exp 1 (n =14), Exp 2 (n =12) Task report C heard: AV-congruent & AV-incongruent Data Visual Speech Index (VSI), calculated on proportion correct audio identifications VSI = [AVcongruent - AVincongruent]