Perceptual adaptation to noise vocoded speech by lipread information: No difference between dyslexic and typical readers

Auditory speech can be difficult to understand but seeing the articulatory movements of a speaker can drastically improve spoken word recognition and on the longer-term, it helps listeners to adapt to acoustically distorted speech. Given that individuals with developmental dyslexia (DD) have sometimes been reported to rely less on lipread speech than typical readers, we examined lipread-driven adaptation to distorted speech in a group of adults with DD (N=29) and a comparison group of typical readers (N = 29). Participants were presented with acoustically distorted Dutch words (6-channel noise vocoded speech, NVS) in audiovisual training blocks (where the speaker could be seen) interspersed with audio-only test blocks. Results showed that words were more accurately recognized if the speaker could be seen (a lipread advantage), and that performance steadily improved across subsequent auditory-only test blocks (adaptation). There were no group differences, suggesting that perceptual adaptation to disrupted spoken words is comparable for dyslexic and typical readers. These data open up a research avenue to investigate the degree to which lipread-driven speech adaptation generalizes across different types of auditory degradation, and across dyslexic readers with decoding versus comprehension difficulties.