# Bimodal Cochlear Implants: Measurement of the Localization Performance as a Function of Device Latency Difference

## TL;DR

Bimodal cochlear implant users struggle with sound localization due to device latency differences, and adjusting these latencies can improve performance, but the optimal adjustment varies among users.

## Contribution

The study identifies that optimal latency adjustments for sound localization in bimodal cochlear implants may differ from previously assumed frequency-independent compensation methods.

## Key findings

- Adjusting interaural latency improves localization performance in most bimodal cochlear implant users.
- Optimal latency for best localization was often shorter than the estimated compensation latency at intermediate frequencies.
- Nine out of eleven subjects localized best with a shorter cochlear implant latency than expected.

## Abstract

Bimodal cochlear implant users show poor localization performance. One reason for this is a difference in the processing latency between the hearing aid and the cochlear implant side. It has been shown that reducing this latency difference acutely improves the localization performance of bimodal cochlear implant users. However, due to the frequency dependency of both the device latencies and the acoustic hearing ear, current frequency-independent latency adjustments cannot fully compensate for the differences, leaving open which latency adjustment is best. We therefore measured the localization performance of 11 bimodal cochlear implant users for multiple cochlear implant latencies. We confirmed previous studies that adjusting the interaural latency improves localization in most of our subjects. However, the latency that leads to the best localization performance for most subjects was not necessarily at the latency estimated to compensate for the interaural difference at intermediate frequencies (1 kHz). Nine of 11 subjects localized best with a cochlear implant latency that was slightly shorter than the estimated latency compensation.