Spoken Language in Adolescents with Hearing Loss

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Project Summary/Abstract Cochlear implants (CIs) and early intervention – made feasible by newborn hearing screenings – have significantly improved the prognosis that children born with hearing loss (HL) will be able to develop spoken language commensurate to that of their typical peers with normal-hearing (NH). These two advances mean that the average child with HL in elementary school now demonstrates abilities on a range of spoken language measures that are just one standard deviation below the means of those typical peers with NH. Although that level of performance exceeds language abilities attainable before CIs and early intervention were so readily available, these performance levels are not what an average child with HL would be attaining in the absence of HL, and mean performance is not improving. Together those facts represent a critical barrier to progress for both research and clinical practice involving children with HL, and it is that barrier that this project seeks to address. A strong motivation for this work is the finding from earlier investigation showing that children with HL experience a disproportionately larger phonological deficit than the deficit observed for morphosyntactic abilities. That large phonological deficit is presumed to arise due to the poor spectral representations available to listeners with HL, especially if they use CIs. This large phonological deficit is predicted to have cascading effects on other, later-acquired language and literacy functions, which are likely dependent on having keen sensitivity to phonological structure. That prediction is explored on this project with children who have been followed since infancy and are now reaching puberty, believed to be the end of first-language acquisition. The premise underlying this work consists of 3 parts: (1) signal degradation can explain much of the continued language gap of children with HL; (2) that degradation disproportionately affects acquisition of phonological sensitivity, rather than morphosyntactic abilities; and (3) that poor phonological sensitivity will have differential effects on later-learned language skills. In all, 124 children (76 with hearing loss) who participated in a longitudinal study of development since they were infants will be tested on a variety of language, literacy, and psychosocial measures at the conclusion of middle school. The four Specific Aims of the project are to: (1) Assess the speech perception, language, literacy, social, and academic performance of 124 children who participated in a longitudinal project since infancy at the end of middle school. (2) Test the hypothesis that phonological sensitivity (PS) and morphosyntactic abilities (MSA) can be independent of each other, at least for children with HL. (3) Examine earlier precursors to PS and MSA measured in 8th grade. (4) Test the related hypotheses that the acquisition of MSA can be close to normal in the face of signal degradation, as long as children get adequate experience with language, but developing highly refined PS requires having had some experience with more detailed acoustic signals. The impact of the project will be that it will inform future audiological and language interventions for deaf children across childhood.