EUROSPEECH 2001 Scandinavia
Cantonese speakers were asked to identify spoken words as one of six Cantonese words differing only in tone. Words were presented in three modes: auditory-visual (AV), auditory only (AO), and visual only (VO). Performance was equivalent in the AO and AV conditions - there was no augmentation of auditory tone perception when visual information was added. Nevertheless, performance in the VO condition was significantly above chance under certain conditions: for perceivers without phonetic training, but not those with phonetic training; for tone carried on monophthongs, but not diphthongs; for tones spoken in running speech, but not citation form; and for contour tones (involving pitch movement over time), but not level tones (involving minimal pitch movement). Thus there is visual information for tone which is functionally relevant under certain circumstances.
Bibliographic reference. Burnham, Denis / Ciocca, Valter / Stokes, Stephanie (2001): "Auditory-visual perception of lexical tone", In EUROSPEECH-2001, 395-398.