A closer look at stimulation thresholds and spread of excitation in cochlear implants: recording aspects and clinical implications

Hearing is an important element for the human wellbeing. It is, therefore, essential to rehabilitate hearing loss adequately. In case of severe hearing loss, for which a regular hearing aid does not work sufficiently, a cochlear implant (CI) can be a solution. A CI is a device that transmits sound directly to the auditory nerve by electrically stimulating the nerve through an electrode array in the cochlea. These electrical stimuli are perceived as sound. The CI also has a telemetry function, which measures the activity of the auditory nerve. The measured activity, called 'eCAP', provides information about the functioning of the CI and the auditory nerve.This thesis describes our study to the relevance and clinical applicability of the eCAP. We investigated how (under which conditions) eCAPs must be measured for potential clinical use. We therefore evaluated common measurement techniques and proposed some improvements. We also developed completely new eCAP measurement techniques. The thesis provided building blocks for a better understanding of how the CI works and for better fitting the CI to the needs of the individual patient.