An exploratory comparison of utterance durations between children with autism spectrum disorder and children with developmental delays
There are several acoustic variables of interest in the speech output of children with Autism Spectrum Disorder (ASD). These variables include fundamental frequency (perceived as pitch), intensity (perceived as loudness), and the duration of sounds. This study examined the differences in the duration of speech productions in young children with ASD compared to young children with developmental delay (DD) without ASD. Utterance durations were determined from audio recordings of six two-year-old children (3 diagnosed with ASD and 3 diagnosed with DD). Descriptive statistics were calculated for the durations and the number of utterances for each child. These included means, standard deviations, minimums, maximums, and medians. For each child, the utterance durations were graphed across the entire session to explore whether durations changed over time. Finally, the number of utterances per minute were calculated for each child. The children with DD produced a higher number of utterances per minute than the children with ASD. The children with DD produced numerically more utterances than the children with ASD. All of the children appeared to produce utterance durations with comparable descriptive statistics. The visual representation of utterance duration over time for the individual children showed that four of the five children produced variable utterance lengths throughout the session. Although statistical testing for differences was not appropriate, it appeared that the children with DD produced a higher number of utterances per minute than the children with ASD. Future research in this area should include larger scale studies with more children in each cohort to determine if patterns exist within and between groups. Future studies should also consider recording sessions in environments with limited background noise to improve the quality of audio recordings and make it possible to examine additional prosodic elements of speech.