Article
Bimodal Cochlear Implant Latency Mismatch and Compensation – Consequences for Sound Localization (en)
* Presenting author
Abstract:
Individuals with a hearing aid in one ear and a cochlear implant (CI) in the other ear have very poor sound localization abilities. A combination of level, tonotopy, and latency mismatches prevents the exploitation of binaural cues and indicates limited spatial adaptation. Compensating for the estimated latency mismatch by adding a fixed delay to the CI stimulation has been shown to acutely improve sound localization (Angermeier et al., Trends in Hearing, 2023). Here, we measure sound localization error and bias as a function of the additional delay. In line with Angermeier et al. the localization bias shifted towards the hearing aid side with increasing CI latency. The amount of bias shift varied from 1° to 9° per millisecond latency. When using speech instead of noise the trends remained similar, but the bias shift was smaller. A bias-free latency could usually be identified within the tested latency interval. This latency also resulted in one of the smallest RMS localization errors. However, the bias-free CI latency was usually smaller than the latency compensation suggested by Angermeier et al.  The difference between the estimated latency mismatch and the best localization will be discussed with respect to level and tonotopy mismatches and spatial adaptation.