Program Director/Principal Investigator (Last, First, Middle): Gantz, Bruce J. PROJECT SUMMARY - OVERVIEW Cochlear implants (CI) have become the standard of care for managing profound sensorineural hearing loss. These devices provide significant improvement in word understanding in quiet but have limitations in noisy backgrounds. Difficulty understanding speech perception in noise (SiN) in real-world environments is one of the most common complaints of people with any type of hearing impairment who are seeking hearing rehabilitation. We believe that the ability to understand SiN is a product of the auditory periphery as well as plasticity afforded by cortical and cognitive processes. At the level of cortical and cognitive processing, our prior work has identified a suite of cognitive mechanisms, including figure/ground separation and changes in lexical processing that interact with the signal quality to impact SiN outcomes. Upon this progress, we now must expand investigations to better understand the influence of other important factors, such as higher order cognitive processes (e.g., working memory and executive functioning), with high potential to assist improvement in SiN abilities among individuals with hearing loss. Furthermore, understanding the effect of these abilities on communication and socialization in real-world settings and its influence on psychosocial well- being could have long-term impact on cognitive stability. This grant incorporates a multi-pronged approach to parse the critical issues at all auditory system levels and as it relates to understanding in real-world listening. Through utilization of a variety of CI users (e.g., SSD, Bilateral, A+E), we can expand our understanding of: 1) mechanisms involved in loss of residual acoustic hearing and how those can facilitate better preservation outcomes; 2) how listeners adapt to and fuse the A+E information to improve hearing in real-world challenging situations; and 3) whether an individual’s cognitive functioning assist the integration of A+E processing. Furthermore, we recognize that communication difficulties transcend SiN performance; we will investigate mechanisms involved with listening in rapid, quiet, or accented speech, reverberant environments, and missing cues (e.g., wearing face masks). The Iowa Cochlear Implant Clinical Research Center requests competitive renewal of funding. Four research projects and two cores are proposed in this application. We will leverage the unique structure of the P50 and our large cohort of CI subjects from our patient registry to develop predictive models at the group and individual levels incorporating peripheral, cortical, cognitive, and language processing insights to predict outcomes in real-world challenging listening environments (i.e., natural listening environments). The four research projects are highly integrated and depend on data from each other to answer the experimental questions proposed.