Lexical stress and focus-marking in a Greek-speaking child with autism spectrum disorder and children with typical development

The current case study focused on the perception and production skills on lexical stress and focus-marking of a seven-year-old Greek-speaking child with autism spectrum disorder and of seven typically developing peers. For the assessment of the above skills four tasks were used; one for the perception of lexical stress one for its production, one for the perception of focus and one for its production. The productions elicited in the production tasks were analysed acoustically using the speech analysis software, PRAAT, and the measurements taken were duration, F0, F1, F2 and intensity of vowels for lexical stress and scaling and alignment of the L and H tones of the prenuclear and nuclear pitch accent for focus. Duration of segments of the stressed syllables of the target word in prenuclear and nuclear position was also measured for focus. The analysis showed that the ASD child performed worse than the control group in the perception and production of lexical stress and in the production of focus but not in its perception where he performed similarly to the controls. It also showed that the number of syllables and the position of focus in the sentence affected his performance. The control group’s performance was only affected by the position of focus. The acoustic analysis showed that the ASD child reduced duration, F0, F1, F2 and intensity in the unstressed condition as the TD group did, showing typical manifestation of stress. He also exhibited some differences in duration, intensity F1 and F2 but not in F0 compared to the controls. When it came to scaling, he realized the H tone of the prenuclear and nuclear pitch accent lower than the control group with no significant differences in the alignment of L and H tones. Lastly, regarding the duration of segments of the stressed syllable of the focused word he did not exhibit any differences compared to the controls however, these segments were atypically longer for him in the prenuclear position. In the study it was also found that the scaling and alignment of the tones of the prenuclear and nuclear pitch accents produced by typically developing children were for the most part in line with the relevant literature on Greek adult speech, however further study is needed including a control group of Greek typically developed adults. Since this was a case study, we could not make any generalizations and arrive to conclusions regarding these prosodic functions in Greek-speaking children with autism spectrum disorder and thus, only initiated a preliminary discussion.