Nivedita Mani and Signe Schneider (2013)

Speaker Identity Supports Phonetic Category Learning.

Journal of Experimental Psychology. Human Perception & Performance, 39(3):623-629.

Visual cues from the speaker's face, such as the discriminable mouth movements used to produce speech sounds, improve discrimination of these sounds by adults. The speaker's face, however, provides more information than just the mouth movements used to produce speech--it also provides a visual indexical cue of the identity of the speaker. The current article examines the extent to which there is separable encoding of speaker identity in speech processing and asks whether speech discrimination is influenced by speaker identity. Does consistent pairing of different speakers' faces with different sounds--that is, hearing one speaker saying one sound and a second speaker saying the second sound--influence the brain's discrimination of the sounds? ERP data from participants previously exposed to consistent speaker-sound pairing indicated improved detection of the phoneme change relative to participants previously exposed to inconsistent speaker-sound pairing--that is, hearing both speakers say both sounds. The results strongly suggest an influence of visual speaker identity in speech processing.