Effects of background noise on cortical encoding of speech in autism spectrum disorders.

This study provides new evidence of deficient auditory cortical processing of speech in noise in autism spectrum disorders (ASD). Speech-evoked responses (approximately 100-300 ms) in quiet and background noise were evaluated in typically-developing (TD) children and children with ASD. ASD responses showed delayed timing (both conditions) and reduced amplitudes (quiet) compared to TD responses. As expected, TD responses in noise were delayed and reduced compared to quiet responses. However, minimal quiet-to-noise response differences were found in children with ASD, presumably because quiet responses were already severely degraded. Moreover, ASD quiet responses resembled TD noise responses, implying that children with ASD process speech in quiet only as well as TD children do in background noise.