Effect of Synchronized Linked Band Selection on Speech Intelligibility of Bilateral Cochlear Implant Users

Abstract

Normal hearing listeners have the ability to exploit the audio input perceived by each ear to extract target information in challenging listening scenarios. Bilateral cochlear implant (BiCI) users, however, do not benefit as much as normal hearing listeners do from a bilateral input. In this study, we investigate the effect that bilaterally linked band selection, bilaterally synchronized electrical stimulation and ideal binary masks (IdBMs) have on the ability of 10 BiCIs to understand speech in background noise. The performance was assessed through a sentence-based speech intelligibility test, in a scenario where the speech signal was presented from the front and the interfering noise from one side. The linked band selection relies on the most favorable signal-to-noise-ratio (SNR) ear, which will select the bands to be stimulated for both CIs. Results show that no benefit from adding a second CI to the most favorable SNR side was achieved for any of the tested bilateral conditions. However, when using both devices, speech perception results show that performing linked band selection, besides delivering bilaterally synchronized electrical stimulation, leads to an improvement compared to standard clinical setups. Moreover, the outcomes of this work show that by applying IdBMs, subjects achieve speech intelligibility scores similar to the ones without background noise.

The Impact of Synchronized Cochlear Implant Sampling and Stimulation on Free-Field Spatial Hearing Outcomes: Comparing the ciPDA Research Processor to Clinical Processors

“…The results presented here agree with other work examining strategies aimed at improving binaural hearing outcomes. For example, Gajecki and Nogueira (2020) investigated the impact of synchronized stimulation and signal processing on speech in noise understanding. They found that both synchronized stimulation and signal processing were necessary to significantly improve SRM.…”

“…They found that both synchronized stimulation and signal processing were necessary to significantly improve SRM. It should be noted that the experimental condition in Gajecki and Nogueira (2020) is somewhat simpler than the one used in these experiments, where the masking talker was located on one side of the head. In this scenario, there is an ear with a significantly improved SNR, which means that the benefits of binaural listening such as squelch and summation might have been underestimated.…”

Transmission of Binaural Cues by Bilateral Cochlear Implants: Examining the Impacts of Bilaterally Independent Spectral Peak-Picking, Pulse Timing, and Compression

“…Linked spectral peak-picking did not significantly affect auditory motion discrimination, although some participants showed benefit (Dennison et al., 2019). In addition, some research suggests that linked spectral peak-picking improves speech understanding in spatially separated noise (Gajecki & Nogueira, 2020). A modeling study suggested that independent spectral peak-picking would negatively affect BiCI localization (Kelvasa & Dietz, 2015), and that independent processing could under some conditions cause stronger stimulation on contralateral electrodes and therefore create opposite-signed ILDs.…”

“…A non-peak-picking stimulation strategy such as CIS could serve this purpose, as could an experimentally linked peak-picking strategy (cf. Gajecki & Nogueira, 2020). Some evidence suggests that the different stimulation strategies implemented across CI manufacturers and devices may afford listeners varying localization performance (Killan et al., 2019), a result that could be further informed by future empirical recordings from a variety of devices.…”