Effect of blindness on mismatch responses to Mandarin lexical tones, consonants, and vowels

According to the hypothesis of auditory compensation, blind listeners are more sensitive to auditory input than sighted listeners. In the current study, we employed the passive oddball paradigm to investigate the effect of blindness on listeners' mismatch responses to Mandarin lexical tones, consonants, and vowels. Twelve blind and twelve sighted age- and verbal IQ-matched adults with normal hearing participated in this study. Our results indicated that blind listeners possibly had a more efficient pre-attentive processing (shorter MMN peak latency) of lexical tones in the tone-dominant hemisphere (i.e., the right hemisphere); and that they exhibited greater sensitivity (larger MMN amplitude) when processing phonemes (consonants and/or vowels) at the pre-attentive stage in both hemispheres compared with sighted individuals. However, we observed longer MMN and P3a peak latencies during phoneme processing in the blind versus control participants, indicating that blind listeners may be slower in terms of pre-attentive processing and involuntary attention switching when processing phonemes. This could be due to a lack of visual experience in the production and perception of phonemes. In a word, the current study revealed a two-sided influence of blindness on Mandarin speech perception.