Matching heard and seen speech: An ERP study of audiovisual word recognition.

Seeing articulatory gestures while listening to speech-in-noise (SIN) significantly improves speech understanding. However, the degree of this improvement varies greatly among individuals. We examined a relationship between two distinct stages of visual articulatory processing and the SIN accuracy by combining a cross-modal repetition priming task with ERP recordings. Participants first heard a word referring to a common object (e.g., pumpkin) and then decided whether the subsequently presented visual silent articulation matched the word they had just heard. Incongruent articulations elicited a significantly enhanced N400, indicative of a mismatch detection at the pre-lexical level. Congruent articulations elicited a significantly larger LPC, indexing articulatory word recognition. Only the N400 difference between incongruent and congruent trials was significantly correlated with individuals' SIN accuracy improvement in the presence of the talker's face.