Electrophysiological correlates of spectral discrimination for cochlear implant users

A cochlear implant (CI) can partially restore hearing in patients with severe to profound sensorineural hearing loss. Proper programming and evaluation of the CIs are key aspects determining success in the restoration of hearing for patients. Recent evidence suggests that cortical auditory evoked potentials, elicited via an unattended oddball paradigm, can provide objective information on CI spectral discrimination abilities, which in turn may be useful for assessing speech perception performance. This study investigates the applicability of an acoustic change paradigm for objective evaluation of CI users´ ability to resolve spectral content via single channel electroencephalography. Acoustic change complex (ACC) responses were obtained from 13 CI users and correlated with psychoacoustic spectral discrimination abilities. The applicability of the acoustic change paradigm was compared to that of the unattended oddball paradigm. The neural spectral discrimination threshold, estimated via the ACC responses, showed a non-significant correlation with the behavioral spectral discrimination threshold. In contrast, the neural spectral threshold estimated via an unattended oddball paradigm showed a significant correlation with the behavioral threshold. Results suggest that the unattended oddball paradigm is a more robust paradigm than the ACC to objectively evaluate CI users´ ability to resolve spectral ripples. Nonetheless, the ACC can be used in some CI users and may be considered as an additional tool for objective evaluation of CI performance.