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Hearing and Donuts (Brain and Bagels) Seminar
September 20, 2019 @ 8:30 am - 9:30 am
Presenter: Ellen Peng, Postdoctoral researcher (Litovsky lab), Waisman Center
Topic: Binaural Sensitivity in Children with Bilateral Cochlear Implants: The Course of Decision-making Revealed by Eye Gaze
Children with severe-to-profound deafness are receiving bilateral cochlear implants (BiCI) at a growing pace world-wide. Typically, they are fitted with two independent devices, and mapping is done separately in each ear. Although they benefit from having two CIs, spatial hearing skills are significantly worse than normal-hearing peers. To understand whether sensitivity to binaural cues, namely interaural time and level differences (ITD and ILD), is the limiting factor for functional abilities, our lab had previously measured just-noticeable-difference (JND) thresholds in children with BiCIs (Ehlers et al., 2017).
Here, we described a new paradigm to measure binaural sensitivity beyond JNDs, by examining the decision-making time-course leading up to behavioral responses. A proof-of-concept study was conducted in children with normal hearing to understand the developmental trajectory of binaural processing as revealed by eye gaze behaviors. Between 8-14 years of age, children with normal hearing demonstrated greater uncertainty than adults when processing ITD cues, even at magnitudes beyond threshold. For children with BiCIs, we used a novel auditory stimulus to successfully deliver ITD and ILD to their clinical processors with enhanced ecological validity. At magnitudes beyond threshold, children with BiCIs showed faster decision-making as ITD or ILD cues became more salient. Together, the novel paradigm provided implications to measure binaural sensitivity both in thresholds and decision-making in children with BiCIs.