BACKGROUND: Autism spectrum disorders (ASD) are a heterogeneous group of disorders encompassing Autistic Disorder, Asperger's Disorder, Semantic-Pragmatic disorder and Pervasive Developmental Disorder Not Otherwise Specified. Auditory integration therapy (AIT) was developed as a technique for improving abnormal sound sensitivity in individuals with behavioural disorders including autism. Other sound therapies bearing similarities to AIT include the Tomatis Method and Samonas Sound Therapy. OBJECTIVES: To determine the effectiveness of AIT or other methods of sound therapy in individuals with ASD. SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (Cochrane Library Issue 2, 2003), MEDLINE (1966 - February 2002), EMBASE (1980 - February 2002), CINAHL (1982 - December 2001), PsycINFO (1887 - February 2002), ERIC (1965 - December 2001) and LILACS (1982 - March 2002). Reference lists of articles identified electronically were searched for further relevant publications. SELECTION CRITERIA: Randomised controlled trials of adults or children with ASD. Treatment was auditory integration therapy (AIT) or other sound therapies involving listening to music modified by filtering and modulation. Control groups could be no treatment, waiting list, usual therapy or placebo equivalent. Outcomes sought were changes in core and associated features of ASD, auditory processing, quality of life and adverse events. DATA COLLECTION AND ANALYSIS: All outcome data reported in included papers were continuous. Initial intention was to undertake meta-analyses using mean difference and standard deviation to take into account differences between treatment and control groups at baseline. These data were not available. Instead, point estimates and standard errors were calculated from t-test scores and post intervention means. Meta-analysis was attempted but deemed inappropriate at present. MAIN RESULTS: No trials assessing sound therapies other than AIT were found. Six RCTs of AIT, including one cross-over trial, were identified with a total of 171 individuals aged 3-39 years. Four trials had fewer than 20 participants. Allocation concealment was inadequate for all of the studies. Seventeen different outcome measures were used. Only two outcomes were used by three or more studies: Aberrant Behaviour Checklist (ABC) (5) and Fisher's Auditory Problems Checklist (FAPC) (3). Meta-analysis was not possible due to very high heterogeneity (Aberrant Behaviour Checklist subscores), or presentation of data in unusable forms. Three studies (Bettison 1996, Zollweg 1997, Mudford 2000) did not demonstrate benefit of AIT over control conditions. The remaining trials (Veale 1993, Rimland 1995, Edelson 1999) reported improvements at 3 months for the AIT group based on improvements of total mean scores for the ABC, which is of questionable validity. Rimland 1995 also reported improvements at 3 months in the AIT group for ABC subgroup scores. No significant adverse effects of AIT were reported. REVIEWER'S CONCLUSIONS: More research is needed to inform parents', carers' and practitioners' decision making about this therapy for individuals with autism spectrum disorders.