Bimodal, CROS and Severe Profound Hearing Loss Study

The study will involve three groups of 20 patients per group. This first is experienced adult bimodal users of the AB system who have usable contralateral residual hearing. A clinical baseline and three research conditions will be evaluated. The Naida CI Link HA (Link) will be fitted, tested and then optimised using a special bimodal fitting formula. Subjects will be allowed three months to acclimatize and will then be retested. The second research condition will evaluate the fully integrated bimodal system, where the microphone signals from CI and HA are shared and a bilateral beamformer is formed. A third intervention will involve modifying the CI settings to minimize the mis-match between frequencies delivered via the CI. A second group with no aidable hearing on their non-implanted ear will also be studied. A contralateral routing of signal (CROS) device will send sounds on the non-implanted side. Tests will be made with and without CROS, as well as with directional microphone settings. Finally as a control group, bilateral HA users will be tested with the similar HA fitting as used for the bimodal group. This will enable a comparison of standard fitting protocols against the new rationale using the same devices.