Evidence for early encoding of speech in blind people

Abstract

Blind listeners rely more on their auditory skills than the sighted to adapt to unavailable visual information. However, it is still unclear whether the blind has stronger noise-related modulation compared with the sighted when speech is presented under adverse listening conditions. This study aims to address this research gap by constructing noisy conditions and syllable contrasts to obtain auditory middle-latency response (MLR) and long-latency response (LLR) in blind and sighted adults. We found that blind people showed higher MLR (Na, Nb, and Pa) and N1 amplitudes compared with sighted, while this phenomenon was not observed for mismatch negativity (MMN) during auditory discrimination in both quiet and noisy backgrounds, which might eventually affect stream segregation and facilitate the understanding of speech in complex environments, contributing to their more sensitive speech detection ability of blind people. These results had important implications regarding the interpretation of noise-induced changes in the early encoding of speech in blind people.