Background and Aim: Autism is a pervasive developmental disorder with several speech disorders such as prosodic and pragmatic impairments. Melodic intonation therapy (MIT) based on Albert et al. model (1973) is a rehabilitation method, developed on prosodic features. The aim of this study was to investigate the effects of MIT on Persian autistic children’s prosody.

Methods: An easy version of MIT, adopted for Persian language was designed by researchers. Then, after a successful pilot study on a 10-years-old boy for one month, 13 subjects were selected for the main study. All the subjects were autistic, male, right-handed, 7-10-years-old Persian children studied for 48 sessions (16 weeks). Background information gathered from the parents by a questionnaire. As pre- and post-test, some assessments about children’s fundamental frequency (Fº) and intensity of the Persian vowel sounds and declarative and interrogative sentences were accomplished. The data analysis was done using Praat and SPSS softwares.

Results: There was a statistically significant increase in acoustic features, such as intensity, and fundamental frequency of declarative and interrogative sentences also all six vowels of Persian, excluding /â/ and /æ/ (p<0.05 for all).

Conclusion: The widely reported unusual prosody in autistic children was quantified by this study, too. In addition, there was convincing evidence of the positive effects of melodic intonation therapy on acoustic features in Persian autistic children.