Atypical Auditory Perception in Autism Spectrum Disorder: A Synthetic Approach to Evaluate the Perceptual Patterns and Environmental Causes

Background: Atypical perception was reported as a potential cause of social difficulties in autism spectrum disorder (ASD). The subjective reports from people with ASD indicated that the atypical perception varies depending on the environmental context. However, it is not easy for everyone to describe their perceptual experiences. Further, the traditional subjective reports are insufficient for quantitative analysis. Therefore, the previous reports could not clarify the detailed patterns of the perception and the influence of environmental factors. In order to solve the problem, a previous study [Nagai et al., 2015] has proposed a synthetic approach to investigate atypical visual perception in ASD. Nevertheless, the understanding of atypical perception in other modalities is still insufficient.

Objectives: According to the previous reports from people with ASD, we assume atypical perception would be affected by environmental stimuli. This study aims at investigating the patterns and environmental causes of atypical auditory perception in ASD. We employed a synthetic approach to lead the participants to systematically report their auditory perception, and then quantitatively analyzed the reports.

Methods: Twenty-two adults with ASD (12 males; age: mean = 30.7, SD = 10.0) were recruited in this study. We presented 30 videos with different scenes and 7 auditory filters (amplify, noise, sine wave, band-reject, echo, flanger, and water effect), which were designed to simulate potential patterns of atypical auditory perception, to the participants. The participant can adjust the strength of the filters to change the sound. The task was using the filters to make the sound similar to his/her auditory perception. We conducted principal component regression on the strength values of the filters and the audiovisual features of the videos.

Results: We found significant regressions on the perception of amplify (F = 2.892, p = 0.002), echo (F = 2.298, p = 0.012), and noise (F = 2.014, p = 0.030). There was a marginally significant regression on the perception of band-reject (F = 1.841, p = 0.051). We checked the audiovisual features which correspond to the significant principal components. The results showed a negative correlation between the perception of amplify and the intensity of video sound. The perception of echo was positively correlated with the mean and the change of both video sound intensity and object movement in the scene. The perception of noise was positively correlated with the mean and the change of sound intensity. There was no clear correlation between the perception of band-reject and audiovisual features. However, the participants reported that the perception of band-reject has occurred due to the sound of human speech.

Conclusions: This study revealed the patterns and the potential environmental causes of atypical auditory perception in ASD. We found there are similar patterns between our results and the atypical visual perception in the previous study, e.g. visual perception of enhanced brightness and the perception of amplify are both sensory enhancements, and snow-like noise in visual perception may be related to the auditory perception of noise. It implies that there exist common neural mechanisms for the atypical perception of seeing and hearing.