Placing a Perceptual Spotlight on Sound: Selective Attention and its Relation to Speech Recognition in Children with Normal Hearing and Hearing LossPublic
Speech recognition in complex acoustic environments is dependent on myriad bottom-up (i.e., peripheral) and top-down (i.e., central) processes. While bottom-up processes remain fairly stable during childhood, the development of top-down processes persists into young adulthood. The immaturity of top-down processes places younger children at considerable risk for poorer speech recognition in complex acoustic environments, which has consequences for academic success and social wellbeing. This is an especially important consideration for children with hearing loss who oftentimes have greater difficulty understanding speech despite restored access to the acoustic characteristics of speech through the use of clinical hearing devices. Therefore, elucidating the factors that influence the development of top-down processes during childhood is important in order to bolster children’s speech recognition in complex acoustic environments. Selective attention is a specific top-down process expected to underlie children’s ability to understand speech in complex acoustic environments by placing a perceptual “spotlight” on the target speech to be further processed. While previous research has provided evidence of the development of selective attention during childhood, the effects of disrupted auditory experience on this development remain largely unknown. Additionally, only a few studies have directly tested the relation between selective attention and speech recognition in children, and the results of these studies have been mixed. This dissertation aimed to address these gaps in knowledge by investigating the effects of age and hearing loss on selective attention during childhood, and quantifying the extent to which selective attention contributes to children’s speech recognition in complex acoustic environments. Children between 5 and 12 years of age with normal hearing and hearing loss participated in two studies to test the hypotheses that: 1) immaturity and disrupted auditory experience impede selective attention during childhood (Chapter 2); and 2) children’s ability to selectively attend to a target speech stream and inhibit attention to competing auditory input contributes to their speech recognition (Chapter 3). In the first study, children performed a behavioral change detection task in the auditory and visual domains during which they were instructed to selectively attend to and detect deviant stimuli within a target stream while inhibiting attention to a distractor stream. Results revealed that younger children and children with hearing loss responded less frequently to deviants in the target stream and more frequently to deviants in the distractor stream, which is indicative of poorer selective attention, than older children and children with normal hearing. Notably, these age- and hearing status-related differences were observed across the auditory and visual domains. In the second study, the same children performed a speech recognition task across acoustic conditions that differed based on reverberation time, masker type, and the spatial location of the masker. Younger children and children with hearing loss demonstrated poorer speech recognition than older children and children with hearing loss. Additionally, children’s ability to selectively attend to a target speech stream was significantly predictive of their ability to understand speech, especially under acoustic conditions expected to impose greater attentional demands. Together, the findings from this dissertation provide novel insight regarding the relations among age, hearing loss, selective attention, and speech recognition during childhood. By demonstrating that age- and hearing status-related differences in selective attention account for observed variability in children’s speech recognition, this work has the potential to inform targeted interventions to maximize children’s academic success and social wellbeing.
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