Online adjustment of phonetic expectation of lexical tones to accommodate speaker variation: a combined behavioural and ERP study

An unresolved question in speech perception is how speech signals with speaker variation are mapped onto their perceptual representations. In this study, this issue was examined using a written-word/spoken-word matching paradigm, where listeners could adjust phonetic expectations of spoken words carrying lexical tones according to speaker-specific F0 cues contained in a preceding speech context, to analyse the tone of the incoming spoken word. Behavioural results showed that Cantonese listeners perceived spoken words differently, in a way compatible with the adjustment of F0 expectations of lexical tones to accommodate between- and within-speaker variation in F0. Electrophysiologically, effects of F0 expectation adjustment were found in the phonological mapping negativity (PMN) time-window (250–310 ms after spoken word onset). These results suggest that phonetic representations of lexical tones are adjustable in a speaker- and context-specific manner, with the adjustment occurring no later than pre-lexical phonemic processing. These findings are consistent with exemplar theory.