The effect of synchronized linked band selection on speech intelligibility of bilateral cochlear implant users

Normal-hearing (NH) listeners have the ability to combine 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 NH listeners do from a bilateral input. In this study, we investigate the effect that bilaterally synchronized electrical stimulation, bilaterally linked band selection, 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. Speech perception results show that BiCI listeners benefit from adding a second CI to the better-SNR side, obtaining the largest benefit when using bilaterally linked band selection and bilaterally synchronized electrical stimulation. Furthermore, synchronized linked band selection leads to an improvement in speech intelligibility scores when compared to standard clinical BiCI setups. Finally, we observe that by also applying IdBMs, subjects achieve speech intelligibility scores similar to the ones without background noise.