Dr. Ruth Litovsky
Professor in the Department of Communication Sciences and Disorders
Impact of auditory deprivation and plasticity on binaural hearing in cochlear implant users
Our lab studies children and adults who receive bilateral cochlear implants (BiCI), or adults with single-sided deafness receiving a CI in the deaf ear (SSD-CI). When patients have access to bilateral hearing they typically improve at localization of sounds and segregation of speech from background noise compared with unilateral hearing. However, patients typically perform worse than normal hearing listeners. We use several approaches to understand mechanisms driving gaps in performance. One important factor we consider in our studies is the age at onset of deafness and age at implantation, which contribute to recovery of binaural hearing. Importantly, CI processors fail to preserve binaural cues with fidelity. We use research processors to generate novel binaural stimulation strategies to test theories about how to restore binaural sensitivity while retaining good speech understanding. In addition, we use eye gaze measures to reveal developmental factors involved in decision-making that are not observed with measures of sensitivity. Finally, by measuring pupil dilation as a proxy for listening effort, we gain insight into the impact of integrating inputs from two ears. While in some instances we observe that patients’ speech understanding improves along with reduced pupil dilation, in other cases improved speech understanding is “costly” in that patients show increased listening effort.