Afua Blay

Date of Award

January 2018

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Communication Sciences & Disorders

First Advisor

Amebu Seddoh

Abstract

Studies on intonation production and perception in children with developmental language impairment (LI) have reported mixed outcomes. Some suggest that intonation processing is impaired in this population but others fail to find any evidence of such a deficit. The issue is further complicated by findings that indicate that these children perform poorly on some intonation tasks but not on others. The source of the discrepant findings is unclear. However, one shortcoming is that most previous studies do not report information on severity of LI of participants. Thus, it may be that the mixed findings on intonation processing in children with developmental language impairment is attributable to severity of the disorder. The present study sought to investigate this possibility. Participants were 33 children with LI and 36 age-matched typically developing controls. Thirteen of the children in the experimental group had mild, 10 had moderate and 10 had severe language impairment. In two experiments, these children’s ability to produce (Experiment 1) and perceive (Experiment 2) intonation was assessed. In Experiment 1, participants were asked questions which required them to respond using broad or narrow focus constructions. Fundamental frequency, tonal alignment, word duration and intensity of the intonation contours produced were measured. In experiment 2, participants were presented sentences produced in broad and narrow focus and asked to discriminate between the two types of constructions. The results showed that children with mild LI performed comparably with typically developing peers on the production of all measures. However, the moderate and severe groups demonstrated difficulty producing word duration and intensity. In the perceptual experiment, all children with LI had difficulty discriminating between broad and narrow focus, with children in the severe group performing the poorest followed by the moderate and severe groups. The findings of the present study suggest that severity of language impairment plays a role in the discrepant findings on intonation processing in children with LI. It also suggests that these children may have more difficulty in the production of some acoustic correlates of intonation compared to others. The implications of these findings are discussed.

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