ELEPHANT

In search of the best possible outcome for the severe hearing impaired who have regained the ability to hear by means of a cochlear implant (CI), electrical stimulation and the information it carries should match as closely as possible to what the human brain naturally has evolved to cope with and learned to process instead of relying on plasticity to adapt to an induced mismatch. At the moment, however, CI’s are fitted with a ‘one size fits all’ principle. This is known to cause a mismatch between the frequencies presented by the CI electrode array and the frequencies represented at the corresponding natural acoustic location in an individual cochlea.



In this study it is hypothesized that an individual imaged based fitting that pursues natural hearing alignment and is implemented from the start of the rehabilitation process, will improve the individual outcomes of electric hearing. The natural fitting strategy is thought to give rise to a steeper learning curve, result in a better performance in challenging listening situations, improve sound quality, complement better with residual acoustic hearing in the contralateral ear and win the preference of CI-recipients.

In this study it is hypothesized that patients with a cochlear implant will benefit from an individual imaged based fitting that pursues natural hearing alignment and is implemented from the start of the rehabilitation process.

This study has multiple phases. The primary part is set up as a prospective single blinded, daily randomized cross-over clinical trial. In this phase electric hearing will be optimized. When patients retain the use of a contralateral hearing aid, acoustic hearing optimization will be performed in a second phase. During the third phase, patients receive their clinical fit, which will be based on the preferences they have obtained during the study period. More in detail, the study outline can be summarized as follows.



- Phase 1. During the intensive CI-rehabilitation phase, mapping of the electrical input will be based on an individualized natural frequency alignment as estimated with imaging methods. This natural fitting will be compared to the standard frequency alignment. A daily randomization scheme will be applied whereby the subject crosses over between CI fitting programs and thus effectively acting as his own control, followed by a period of free choice between both maps to incorporate patient preference. Outcome measures will be assessed at several single points, to address the difference between both CI maps, as well as over time, to address the learning curve with both CI maps.

- Phase 2. After a period of 6 months a stable outcome with CI is expected. When patients retain the use of a contralateral hearing aid up to this time point, the fitting of the acoustic hearing aid will be optimised and compared to the standard fitting. Outcome measures will be assessed acutely and at the end of a take-home period.

- Phase 3. At this time point, patients have indicated their final preference for either the conventional or bimodal HA fitting. In combination with the preferred CI settings, as indicated at the end of phase 1, a clinical fit will be performed for both CI and HA.

Two interventions will be implemented during the study.



1. During the intensive CI-rehabilitation phase, mapping of the electrical input will be based on an individualized natural frequency alignment as estimated with imaging methods. This natural fitting will be compared to the standard frequency alignment. A daily randomization scheme will be applied whereby the subject acts as his own control, followed by a period of free choice between both maps. Outcome measures will be assessed at several single points, to address the difference between both CI maps, as well as over time, to address the learning curve with both CI maps.



2. In a second stage, after a stable outcome with CI is reached and if a contralateral hearing aid is used, the fitting of the acoustic hearing aid will be optimised and compared to the standard fitting. Outcome measures will be assessed acutely and at the end of a take-home period.