Project Summary/Abstract Children with hearing loss are at risk for significant language delays, which cascade into difficulties in educational and vocational settings throughout the lifespan. However, language delays in children with hearing loss are not universal; some children fall significantly behind children with normal hearing (CNH), while others perform similarly to CNH. Recent work in children with mild-to-severe hearing loss (i.e., children who are hard-of-hearing [CHH]) who wear hearing aids suggests that the degree of language impairment correlates with auditory dosage, defined by both the degree to which a hearing aid provides access to speech and the amount of hearing aid use. Nonetheless, the relationship between auditory access (i.e., hearing loss and auditory dosage) and language function is still unclear. Further, the impact of auditory access on language-related neural oscillatory dynamics is completely unknown. The proposed early-career R21 project will provide pivotal new data on the impact of variability in auditory access on multiple tiers of language function and neuronal dynamics in school-age children. Our promising preliminary work shows that noninvasive imaging with magnetoencephalography (MEG) can precisely detect the neural patterns supporting language processing throughout the left-lateralized language network in children and can quantify the relationship between altered neuronal activity and auditory dosage in CHH. In the current study, we will characterize the associations between auditory access, language processing, and neural development in a large cohort of CHH and demographically matched CNH. Participants will undergo task-based MEG during a battery of language tasks, structural MRI, and neuropsychological and audiometric testing. In Aim 1, we will identify the spatiotemporal oscillatory dynamics that underlie the behavioral differences in language processing observed between CHH and demographically matched CNH. Deficits in language processing in CHH will be coupled with increased task-related neural activity and altered functional connectivity throughout the left-lateralized language network. CHH will also recruit homologous language-related regions in the right hemisphere, indicative of a compensatory mechanism, and network-level oscillatory aberrations will predict task performance. In Aim 2, we will characterize the impact of auditory dosage on language processing performance and neurophysiology. We hypothesize that CHH with higher auditory dosage will exhibit better performance in language tasks and more normalized language-related neural activity. Further, we hypothesize that the individual contributions of hearing aid use and fit will depend on the degree of hearing loss, such that hearing aid use will have a greater effect on children with milder hearing loss, while hearing aid audibility will be the more significant factor in children with more severe hearing loss. This study will provide precise, quantitative markers supporting key facets of language development and will identify the individual and additive contributions of malleable auditory factors such as hearing aid fit and use. These data will help characterize the nature of language impairments in CHH and be used to optimize therapeutic interventions.

Narrative It is well established that children with mild-to-severe hearing loss are at risk for significant language delays compared to children with normal hearing, and language deficits are exacerbated by poor hearing aid fitting and inconsistent hearing aid use. However, the underlying neural mechanisms remain unknown, as very few studies have examined how such hearing loss affects the brain dynamics serving language processing in these children. The proposed study will determine the impact of mild-to-severe hearing loss and the role of hearing aid use and fit on multiple facets of language processing in children using a cutting-edge multimodal neuroimaging approach coupled with advanced behavioral and neuropsychological measures.