Hearing impairment disrupts processes of selective attention that help listeners attend to one sound source over competing sounds in the environment. Hearing prostheses (hearing aids and cochlear implants, CIs), do not fully remedy these issues. In normal hearing, mechanisms of selective attention arise through the facilitation and suppression of neural activity that represents sound sources. However, it is unclear how hearing impairment affects these neural processes, which is key to understanding why listening difficulty remains. Here, severely-impaired listeners treated with a CI, and age-matched normal-hearing controls, attended to one of two identical but spatially separated talkers while multichannel EEG was recorded. Whereas neural representations of attended and ignored speech were differentiated at early (~ 150 ms) cortical processing stages in controls, differentiation of talker representations only occurred later (~250 ms) in CI users. CI users, but not controls, also showed evidence for spatial suppression of the ignored talker through lateralized alpha (7–14 Hz) oscillations. However, CI users’ perceptual performance was only predicted by early-stage talker differentiation. We conclude that multi-talker listening difficulty remains for impaired listeners due to deficits in early-stage separation of cortical speech representations, despite neural evidence that they use spatial information to guide selective attention.

Objective: To (i) demonstrate the utility of geographically weighted Poisson regression (GWPR) in describing geographical patterns of adult cochlear implant (CI) incidence in relation to sociodemographic factors in a publicly funded healthcare system, and (ii) compare Poisson regression and GWPR to fit the aforementioned relationship. Study Design: Retrospective study of provincial CI Program database. Setting: Academic hospital. Patients: Adults 18 years or older who received a CI from 2020 to 2021. Intervention(s): Cochlear implant.Main Outcome Measure(s): CI incidence based on income level, education attainment, age at implantation, and distance from center, and spatial autocorrelation across census metropolitan areas. Results: Adult CI incidence varied spatially across Ontario (Moran's I = 0.04, p < 0.05). Poisson regression demonstrated positive associations between implantation and lower income level (coefficient = 0.0284, p < 0.05) and younger age (coefficient = 0.1075, p < 0.01), and a negative association with distance to CI center (coefficient = −0.0060, p < 0.01). Spatial autocorrelation was significant in Poisson model (Moran's I = 0.13, p < 0.05). GWPR accounted for spatial differences (Moran's I = 0.24, p < 0.690), and similar associations to Poisson were observed. GWPR further identified clusters of implantation in South Central census metropolitan areas with higher education attainment. Conclusions: Adult CI incidence demonstrated a nonstationary relationship between implantation and the studied sociodemographic factors. GWPR performed better than Poisson regression in accounting for these local spatial variations. These results support the development of targeted interventions to improve access and utilization to CIs in a publicly funded healthcare system.