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

Gajęcki, Tom; Nogueira, Waldo

doi:10.1016/j.heares.2020.108051

Cited by 10 publications

(14 citation statements)

References 37 publications

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“…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.…”

Section: Discussionmentioning

confidence: 99%

“…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.…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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Acoustic hearing listeners use binaural cues—interaural time differences (ITDs) and interaural level differences (ILDs)—for localization and segregation of sound sources in the horizontal plane. Cochlear implant users now often receive two implants (bilateral cochlear implants [BiCIs]) rather than one, with the goal to provide access to these cues. However, BiCI listeners often experience difficulty with binaural tasks. Most BiCIs use independent sound processors at each ear; it has often been suggested that such independence may degrade the transmission of binaural cues, particularly ITDs. Here, we report empirical measurements of binaural cue transmission via BiCIs implementing a common “ n-of- m” spectral peak-picking stimulation strategy. Measurements were completed for speech and nonspeech stimuli presented to an acoustic manikin “fitted” with BiCI sound processors. Electric outputs from the BiCIs and acoustic outputs from the manikin’s in-ear microphones were recorded simultaneously, enabling comparison of electric and acoustic binaural cues. For source locations away from the midline, BiCI binaural cues, particularly envelope ITD cues, were found to be degraded by asymmetric spectral peak-picking. In addition, pulse amplitude saturation due to nonlinear level mapping yielded smaller ILDs at higher presentation levels. Finally, while individual pulses conveyed a spurious “drifting” ITD, consistent with independent left and right processor clocks, such variation was not evident in transmitted envelope ITDs. Results point to avenues for improvement of BiCI technology and may prove useful in the interpretation of BiCI spatial hearing outcomes reported in prior and future studies.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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

et al. 2021

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“…Using an objective method of analysis on a manikin that wore a BiCI, Kan et al [17] reported that 'n-of-m' processing resulted in inaccurate ITD encoding. In BiCI users, independent band selection has been found to reduce the sentence recognition score (SRS) in noise compared to binaurally linked band selection [33]. However, the effect of independent band selection on the SRM has not been studied.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, sine wave vocoders were implemented to simulate some of the characteristics of cochlear implant signal processing in this study. Speech recognition in noise and SRM were chosen as the experimental tools in this study because of the reported utility of these tools to study the effect of interaural frequency mismatches on binaural processing in BiCI [17,28,32,33,35,36].…”

Section: Introductionmentioning

confidence: 99%

Effect of interaural electrode insertion depth difference and independent band selection on sentence recognition in noise and spatial release from masking in simulated bilateral cochlear implant listening

Fathima

Bhat

Pitchaimuthu

2023

Eur Arch Otorhinolaryngol

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Purpose Inter-aural insertion depth difference (IEDD) in bilateral cochlear implant (BiCI) with continuous interleaved sampling (CIS) processing is known to reduce the recognition of speech in noise and spatial release from masking (SRM). However, the independent channel selection in the ‘n-of-m’ sound coding strategy might have a different effect on speech recognition and SRM when compared to the effects of IEDD in CIS-based findings. This study aimed to investigate the effect of bilateral ‘n-of-m’ processing strategy and interaural electrode insertion depth difference on speech recognition in noise and SRM under conditions that simulated bilateral cochlear implant listening. Methods Five young adults with normal hearing sensitivity participated in the study. The target sentences were spatially filtered to originate from 0° and the masker was spatially filtered at 0°, 15°, 37.5°, and 90° using the Oldenburg head-related transfer function database for behind the ear microphone. A 22-channel sine wave vocoder processing based on ‘n-of-m’ processing was applied to the spatialized target-masker mixture, in each ear. The perceptual experiment involved a test of speech recognition in noise under one co-located condition (target and masker at 0°) and three spatially separated conditions (target at 0°, masker at 15°, 37.5°, or 90° to the right ear). Results The results were analyzed using a three-way repeated measure analysis of variance (ANOVA). The effect of interaural insertion depth difference (F (2,8) = 3.145, p = 0.098, ɳ2 = 0.007) and spatial separation between target and masker (F (3,12) = 1.239, p = 0.339, ɳ2 = 0.004) on speech recognition in noise was not significant. Conclusions Speech recognition in noise and SRM were not affected by IEDD ≤ 3 mm. Bilateral ‘n-of-m’ processing resulted in reduced speech recognition in noise and SRM.

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“…A major obstruction to accurate source localization by bimodal and bilateral CI users is the distortion of interaural time and level difference cues (ITD and ILD), and limited ITD sensitivity [20]. A number of CI processing strategies involving encoding of the time differences [21], [22] have been developed to resolve this issue to make the experience of hearing as natural as possible to BiCIs. But most of these algorithm advancements present simulated results and have not been verified with subjective results as it is not possible to alter or add the researcher designed-novel processing, on a CI user's clinical processor while subject testing.…”

Section: Introductionmentioning

confidence: 99%

Bilateral Cochlear Implant Processing of Coding Strategies With CCi-MOBILE, an Open-Source Research Platform

Ghosh

Hansen

2023

IEEE/ACM Trans. Audio Speech Lang. Process.

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While speech understanding for cochlear implant (CI) users in quiet is relatively effective, listeners experience difficulty in identification of speaker and sound location. To assist in achieving better residual hearing abilities and speech intelligibility support, bilateral and bimodal forms of assisted hearing are emerging as viable options for CI users. Effective bilateral processing calls for testing precise algorithm synchronization and fitting between both left and right ear channels in order to capture interaural time and level difference cues (ITD and ILDs). This work demonstrates bilateral implant algorithm processing using a custom-made CI research platform -CCi-MOBILE, which is capable of capturing precise source localization information and support researchers in testing bilateral CI processing in real-time naturalistic environments. Simulation-based, objective, and subjective testing has been performed to validate the accuracy of the platform. The subjective test results produced an RMS error of ±8.66° for source localization, which is comparative to the performance of commercial CI processors.

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

Cited by 10 publications

References 37 publications

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

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

Effect of interaural electrode insertion depth difference and independent band selection on sentence recognition in noise and spatial release from masking in simulated bilateral cochlear implant listening

Bilateral Cochlear Implant Processing of Coding Strategies With CCi-MOBILE, an Open-Source Research Platform

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