Deficits in Auditory Temporal Processing Are Associated with Language Impairments in Children with ASD

Background: Sensory processing abnormalities are amongst the most commonly reported symptoms associated with autism spectrum disorders (ASD), and are now included in diagnostic criteria for ASD in the DSM-V. Auditory processing is a particular area in which both clinical report and experimental evidence indicate atypicalities in ASD, yet much research is needed to characterize the nature and extent of abnormalities. It has recently been proposed that a diffuse deficit in temporal processing could underlie core symptoms of ASD. Along these lines, our group has shown impairments in the ability of children with ASD to resolve the temporal order of two auditory stimuli presented sequentially at brief intervals. Auditory processing, and auditory temporal processing in particular, have been linked to speech perception and language functioning, two areas that are impacted in ASD. Thus, in the present study, we assess auditory temporal processing and examine the extent to which it is related to language functioning in children with ASD.

Objectives: The aims of this study are to determine whether: 1) children with ASD demonstrate deficits, relative to children with typical development (TD) on a task assessing auditory temporal processing; and 2) auditory temporal resolution is related to measures of language functioning among children with ASD.

Methods: Participants included 24 children with ASD and 27 children with TD, all between 10 and 13 years of age. Children completed a psychophysical thresholding procedure to determine the minimum temporal gap within a stimulus that was needed for them to perceive the interruption (i.e., that the stimulus was not continuous). A staircase procedure manipulated gap size with decreasing step sizes and sequential reversals to converge upon a gap detection threshold for each child. To assess language functioning, children were administered subtests from the Clinical Evaluation of Language Fundamentals–Fourth Edition (CELF-4) and the Comprehensive Test of Phonological Processing (CTOPP).

 Results: Results revealed that children with ASD had significantly higher auditory gap detection thresholds than TD children (p=0.027). Specifically, whereas TD children needed silent intervals of 3.25ms to reliably detect the presence of gaps in auditory stimuli, children with ASD needed gaps of 3.92ms, on average. The difference between groups reflects a 20.6% increase in gap detection threshold in children with ASD, relative to those with TD. Regarding relations to language functioning among children with ASD, a statistically significant correlation was found between auditory gap detection threshold and scores on the CTOPP Blending Words subtest (r= -0.44, p=0.03). Thresholds were also correlated significantly with raw scores from the Concepts and Following Directions (r= -0.41, p<0.05), Word Classes–Receptive (r= -0.67, p<0.001), and Word Classes–Expressive (r= -0.49, p=0.02), subtests of the CELF-4.

Conclusions: Results of this study revealed increased auditory gap detection thresholds in ASD relative to TD controls, suggesting impairments in auditory temporal processing. Among children with ASD, greater difficulty with auditory gap detection was associated with more substantial language-related impairments. These findings provide clues into the etiology of language-based deficits in ASD, and suggest avenues for future research and treatment approaches.