Autistic traits and speech perception in social and non-social noises.

Individuals with the autism spectrum disorder (ASD) experience difficulties in perceiving speech in background noises with temporal dips; they also lack social orienting. We tested two hypotheses: (1) the higher the autistic traits, the lower the performance in the speech-in-noise test, and (2) individuals with high autistic traits experience greater difficulty in perceiving speech, especially in the non-vocal noise, because of their attentional bias toward non-vocal sounds. Thirty-eight female Japanese university students participated in an experiment measuring their ability to perceive speech in the presence of noise. Participants were asked to detect Japanese words embedded in vocal and non-vocal background noises with temporal dips. We found a marginally significant effect of autistic traits on speech perception performance, suggesting a trend that favors the first hypothesis. However, caution is needed in this interpretation because the null hypothesis is not rejected. No significant interaction was found between the types of background noise and autistic traits, indicating that the second hypothesis was not supported. This might be because individuals with high autistic traits in the general population have a weaker attentional bias toward non-vocal sounds than those with ASD or to the explicit instruction given to attend to the target speech.