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

TL;DR

This study investigates how adjusting device latency differences affects localization performance in bimodal cochlear implant users, revealing that most users perform best with slightly shorter latencies than theoretically calculated.

Contribution

It provides empirical data showing optimal latency adjustments vary among users and are often shorter than predicted by frequency-independent models.

Findings

Most users localize best with slightly shorter latencies.

Latency adjustment improves localization performance.

Frequency-dependent latency effects are significant.

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 eleven bimodal cochlear implant users for multiple cochlear implant latencies. We confirm previous studies that adjusting the interaural latency improves localization in all eleven bimodal cochlear implant users. However, the latency that leads to the best localization performance for most subjects was not at the latency calculated to compensate for the interaural difference at intermediate frequencies (1 kHz). Nine of eleven subjects localized best with a cochlear implant latency that was slightly shorter than the calculated latency compensation.