Project Summary: Cochlear implants (CIs) are an effective treatment for adults with severe-to-profound sensorineural hearing loss, and ideally lead to improved real-world communication skills and social engagement. However, we currently do not have a good understanding of relevant, modifiable factors that contribute to the enormous variability in communication outcomes observed in both new and experienced CI users. Further, the current method by which we quantify CI outcomes, via clinical measures of speech recognition, tells us little about the real-world functioning of our CI patients. Our long-term goal is to better understand real-world communication, learning, and adaptation in adult CI users, and the sensory and cognitive-linguistic processes that support maximizing real-world CI benefits, in order to identify future targets for rehabilitative efforts. New CI users largely learn to adapt to their CIs through their everyday experiences. Differences in the real-world auditory- social experience of new CI users likely contribute to communication outcomes, but currently our knowledge of how real-world experience promotes adaptation in adult CI users is limited. Further, the extent to which auditory- social experience changes following implantation remains unclear. Therefore, the overall objectives of the proposed research are to determine how diverse auditory-social experience facilitates speech recognition abilities in new CI users, and to characterize changes in their auditory-social experience, using a multi- disciplinary approach. Here, we focus on the amount and variability of new CI users’ speech input (“speech input attributes”), through assessment of their social networks and communication practices. Our central hypothesis is that speech input variability experienced in the real-world auditory-social environment promotes robust speech recognition abilities in new CI users, and that access to diverse real-world auditory-social experience expands as a benefit of implantation. Our hypothesis will be tested in two Specific Aims: Aim 1 will determine the contribution of speech input attributes experienced in the real-world auditory-social environment to robust speech recognition abilities in new CI users. We will assess the association between new CI users’ experience of speech input variability and amount and speech recognition abilities in challenging conditions, pre- operatively and over 6 months of CI use. Aim 2 will investigate changes in the real-world auditory-social experience of new CI users following implantation, and the moderating role of robust communication skills. We will compare speech input attributes pre-operatively and at 6 months of CI use, and evaluate the relation between changes and speech comprehension ability. The proposed research will lead to a better understanding of modifiable factors (i.e. auditory-social environments) that best support adaptation and will help to define real- world social engagement benefits of...