Longitudinal observation of localization ability of bimodal Cochlear Implant users with matched inter-aural timing

The ability of localizing a sound source is specifically impaired in bimodal Cochlear Implant (CI)-users due to different time delays in signal processing between CI and the contralateral hearing aid (HA). For MED-EL devices the electrical stimulation is generally ahead compared to the acoustical stimulation with different types of hearing aids. Delaying the MED-EL-system by a constant factor better matching the HA-stimulation has been shown to have a positive effect on localization ability already after a short period of acclimatization in experienced bimodal CI-users.

In the current study, the individual mismatch in processing time between HA and CI was reduced already in the first fitting period of the CI. Localization ability in the frontal horizontal plane was measured in a longitudinal approach 1, 3, 6 and 12 months after first fit of the CI. Additionally, localization ability with matched inter-aural timing was compared to performance without inter-aural adaptation.

A large benefit in rms-error of matched bimodal stimulation was observed compared to monaural HA-only performance. For some patients this benefit arrived at a constant level already after one month of bimodal experience. Fewer patients needed longer periods of time to benefit from the second ear. The matched vs. unmatched timing comparison revealed a benefit for matching electrical and acoustical stimulation, especially in cases with larger differences in processing time between both devices.

BMBF Projekt NOBIS

Publication History

Article published online:
24 May 2022