Expressive Prosody in Autism Spectrum Disorders: Meta-Analysis

Objectives: Atypical prosodic expression in autism spectrum disorder (ASD) groups has been reported frequently. This study aimed to synthesize the results of previous studies on the prosody in ASD groups. Methods: A systematic literature review was performed using a meta-analysis method (Comprehensive Meta-Analysis II [CMA2], 2005). Fifteen studies meeting the inclusion criteria were entered into the analysis. The effect size was computed using a random effect model. Results: The results showed the following. Prosodic expression of ASD group was significantly different from typically developing (TD) group. The significant differences were observed in pitch, loudness, and speech rate; the effect size of pitch was the largest one among the three measurements. The prosodic expression of ASD groups was significantly different according to the language units and sampling methods used for analysis. Paragraphs (among the language units) and spontaneous utterance (among the sampling methods) revealed the largest effect sizes. Conclusion: Our findings suggest that there were a significant difference between ASD's and TD's prosodic features. The results should provide an evidence-based rational for prosodic intervention with ASD groups.