Binaural and Spatial Hearing in Implanted Children
Children with normal hearing (NH) utilize information that arrives at the two ears in order to perform a multitude of tasks in their everyday listening environments. In the field of audiology, the question regarding provision of auditory input to one vs. two ears has been around for many years. This chapter has three objectives. First, the potential benefits from having two ears are described, with a focus on binaural cues that are available to listeners when using acoustic hearing, or electric hearing through cochlear implants (CIs). While NH children can access fine-grained binaural cues, bilateral CI users face a number of limitations in the binaural processing domain. A second objective is the discussion of measures that are used to evaluate binaural and bilateral hearing. Binaural sensitivity measures are obtained with acoustic stimuli over headphones or with direct electrical stimulation. Spatial hearing acuity provides a measure of the extent to which children know whether sounds are presented to the right vs. left, but sound localization indicates whether children can map acoustic space to perceived locations. Finally spatial release from masking indicates how well children can understand speech that is within their vocabulary, in the presence of maskers that are spatially co-located or separated from the target. A third objective is to highlight outcomes in children with bilateral CIs, focusing on the emergence of binaural and spatial hearing spanning the range of ~2 years of age to late childhood. Findings in NH and bilaterally implanted children are compared, and the role of auditory deprivation vs. early stimulation is considered.
KeywordsChildren Cochlear implant Bilateral Binaural Localization Speech
The author is very grateful to students, postdoctoral fellows, and collaborators whose participation in the cited studies was important to the success of this chapter, and to the research participants for their dedication to the understanding of bilateral and binaural hearing in children. The author received support for her work from the National Institutes of Health (R01 DC 003083 and 5R01 DC 008365).
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