Children with autism often experience substantial impairments in the domain of language and communication. Speech generating device (SGD) is one of the widely used augmentative communication systems with this population. The most prevalent speech output systems currently in use with SGDs are digitized and synthetic speech outputs. Advantages and disadvantages of each speech output system exist, and large individual differences in-terms of preference and performance have been speculated in both modalities. There is currently no published research that compares digitized and synthetic speech outputs. The primary goal of this study is to examine the effects of SGD training using digitized vs. synthetic speech outputs on the acquisition of requesting skills of 4 non-verbal children diagnosed with autism. The study addressed the following research questions. First, are there differences in acquisition rates for requests taught using digitized vs. synthetic speech outputs? Second, do children show a preference for one speech output over other? Finally, Are there any differences in perceived social validity of digitized vs. synthetic speech outputs? The primary findings of this study were: (1) Differences in the performance were found between two of the participants within each speech output; (2) two of the participants appeared to prefer one speech output over other and one participant could not indicate his preference due to positioning bias; (3) social validity measures indicated favorable ratings for SGD training but no clear indications in-terms of acceptability and usability of speech outputs across different settings. The overall results obtained from this study suggest that speech output can play a significant role, and it is one of the important components that can contribute to the success of the intervention. Additionally, overall outcome suggests that non-verbal children with autism can successfully learn to use the SGDs at their own pace with the support of proper prompting strategies and instructional procedures. / text