Binaural Unmasking in Children with Cochlear Implants

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DESCRIPTION (provided by applicant): Bilateral cochlear implantation in children is becoming increasingly popular in an effort to improve the ability to localize sound sources and understand speech in the presence of interfering stimuli. However, compared to the performance of normally hearing listeners, the binaural advantages that listeners with bilateral cochlear implants receive are limited. Sources of limitations in binaural hearing are currently poorly understood but may include limitations with cochlear implant devices and limitations in auditory system processing of listeners. Stimulation through bilateral cochlear implants provides degraded binaural information relative to the original acoustic signal and may fail to foster binaural hearig in children. Improving knowledge on the sensitivity of children with cochlear implants to binaural cues is necessary for improving technology and treatment of children with cochlear implants. Binaural masking level differences of children with bilateral cochlear implants will be examined using direct electrical stimulation to bypass the clinical cochlear implants and present bilaterall coordinated stimuli. Binaural sensitivity of children with bilateral cochlear implants will be examined relative to adults with bilateral cochlear implants and children with normal hearing. In addition, binaural sensitivity of children with normal hearing will be examined relative to adults with normal hearing. Binaural masking level differences are a measure of the binaural advantage for signal detection in noise. Examination of binaural masking level differences is important as it will improve understanding of limitations in the binaural advantage for segregating speech from noise. This study will further the understanding of binaural sensitivity of children with bilateral cochlear implants by examining binaural masking level differences under stimulus conditions which are relevant to real-world auditory stimuli. Aim 1 will examine the effect of stimulus bandwidth on binaural masking level differences using a single pair of left-right electrodes. Aim 2 will examine the effect of distance between electrodes using two pairs of left-right electrodes. Findings from this study will be informative for advancing cochlear implant technology in ways such that children receive benefits and will improve understanding of the development of the auditory system.