Objective: To evaluate the postoperative changes of the basic electrophysiological and psychophysical parameters in cochlear implant (CI) patients: the impedance of the electrode contacts, the electrically-evoked compound action potential (ECAP) thresholds and the T/C levels. Study Design and Setting: Retrospective case review in a quaternary otologic referral centre. Materials and Methods: Data on the impedance of the electrode contacts, the ECAP thresholds and the T/C levels were collected in 20 consecutive CI patients divided into 2 groups. Group 1 comprised 10 prelingually deaf children implanted before the age of 18 months, and group 2 comprised 10 postlingually deaf adults (average age of 58 years). All patients were users of the Nucleus 24RECA (Freedom, Contour advance off-stylet electrode) CI. Results and Conclusions: (1) The mid-portion and the apical electrodes showed a decrease in the impedance values between the 1st and the 6th postoperative months and stabilization in the later course. Impedance of the most basal electrodes grew during the first postoperative months and stabilized later on, but remained higher than the impedance of the mid-portion and the apical electrodes. (2) The neural response telemetry threshold values tended to decrease within the first 3 months after surgery to reach a plateau afterwards. (3) The behavioural threshold levels remained generally stable, except for the basal electrodes where a decrease could be observed. The hearing comfort levels showed an increase during the first 6 months of the implant use and remained stable afterwards.

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Several studies report that sound localization performance of acute and chronic monauralized normal-hearing listeners can improve through training. Typically, training sessions are administered daily for several days or weeks. While this intensive training is effective, it may also be that monaural localization abilities improve instantly after providing explicit top-down information about the direction dependent change in timbre and level. The aim of the present study was to investigate whether cognitive feedback (i.e., top-down information) could instantly improve sound localization in naive acutely monauralized listeners. Forty-three normal-hearing listeners (experimental group), divided over five different centers, were tested. Two control groups, consisting of, respectively, nine and eleven normal-hearing listeners, were tested in one center. Broadband sounds (0.5–20 kHz) were presented from visible loudspeakers, positioned in azimuth (− 90° to 90°). Participants in the experimental group received explicit information about the noticeable difference in timbre and the poor localization in the monauralized listening condition, resulting in an instant improvement in sound localization abilities. With subsequent roving of stimulus level (20 dB), sound localization performance deteriorated immediately. The reported improvement is related to the context of the localization test. The results provide important implications for studies investigating sound localization in a clinical setting, especially during closed-set testing, and indicate the importance of top-down information.

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