A Monocentric Study Evaluating Pupillometry as an Objective Measurement for CI Fittings

The purpose of the clinical investigation is to explore the pupil dilation response of subjects with a cochlear implant and to provide proof of concept that it is possible to perform the adaptation of a cochlear implant using pupillometry. The population of this study is divided in 2 group: * A control group with normal-hearing listeners. * An Cl group with subjects with bilateral, severe-to-profound sensorineural hearing loss, with at least one cochlear implant for more than 6 months. Mainly used in audiology to evaluate listening effort, pupillometry is an objective measure that could also be used for fittings. Studies have shown that sound intensity influence pupil dilation. indeed, normal hearing and hearing aids subjects exhibit larger pupil responses with increasing intensity/loudness. The purpose of this study is to explore the pupil dilation response of cochlear implant subjects and to provide a proof of concept that we can perform cochlear implant fitting using pupillometry. Implanted subjects (Cl group) will undergo up to 3 visits: 1. Visit 1 or V1(inclusion) on day 1, 2. Visit 2 or V2 (Experiment 1-+2+3 or Experiment 1+2 or Experiment 3 )\* up to 1 month after V1 3. Visit 3 or V3 (Experiment 1+2 or Experiment 3, optional)\* up to 1 month after V2 \*lt is up to investigator decision to conduct experiment 1+2 and experiment 3 the same day or in on independent visit (no matter in which order) Normal-hearing listeners (control group) will undergo up to 2 visits: 1. Visit 1 or Va (inclusion) on day 1, 2. Visit 2 or V2 (experiment) up to 1 month after V1