Effect of stimulus polarity on detection thresholds in cochlear implant users: relationships with average threshold, gap detection, and rate discrimination

Carlyon, Robert P.; Cosentino, Stefano; Deeks, John M.; Parkinson, Wendy; Arenberg, Julie A.

doi:10.1101/297085

Cited by 4 publications

(11 citation statements)

References 43 publications

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“…Moreover, similar observations in clinical studies demonstrated that the polarity sensitivity of ANFs is a potential approach to identify neural health in CI users to improve CI performance and enhance speech perception (Macherey et al, 2008;Van Wieringen et al, 2008;Undurraga et al, 2010;Carlyon et al, 2013Carlyon et al, , 2018Pfingst et al, 2015a,b;DeVries et al, 2016;Schvartz-Leyzac and Pfingst, 2018;Goehring et al, 2019;Jahn and Arenberg, 2019a;Mesnildrey et al, 2020). On the other hand, several studies on human CI recipients reported different and contradictory outcomes by using polarity sensitivity (Macherey et al, 2006(Macherey et al, , 2017Bahmer and Baumann, 2013;Karg et al, 2013;Undurraga et al, 2013;Hughes et al, 2017Hughes et al, , 2018Mesnildrey et al, 2017;Luo J. et al, 2020;Xu et al, 2020).…”

Section: Introductionmentioning

confidence: 87%

“…Despite using triphasic pulse, Carlyon et al (2018) and Jahn and Arenberg (2019a) reported that up to 70% of investigated electrodes showed anodic sensitivity and could not prove polarity behavior as an indicator for estimating neural survival. Similar to their results, we found more anodic sensitivity using asymmetric pulses, such as pseudomonophasic and triphasic pulses, in the perimodiolar array.…”

Section: Effect Of Pulse Shapementioning

confidence: 96%

“…In contrast to symmetric pulses, several studies demonstrated promising results in polarity investigations by using asymmetric pulse shapes, for example, pseudomonophasic and triphasic (Macherey et al, 2006(Macherey et al, , 2008(Macherey et al, , 2017Carlyon et al, 2013Carlyon et al, , 2018Undurraga et al, 2013;Bahmer et al, 2017;Mesnildrey et al, 2017;Jahn and Arenberg, 2019a). However, some of these studies could not provide direct evidence to prove the role of the polarity effect in estimating neural health, which might result from various factors such as stimulation strategy and CI systems.…”

Section: Effect Of Pulse Shapementioning

confidence: 99%

“…Many techniques have been introduced to examine the neural status in CI users, such as pulse rate, pulse polarity, stimulation mode, interphase gap, and phase duration. These techniques revealed substantial outcome variations between subjects and electrodes during psychophysical and electrophysiological measures ( Pfingst and Xu, 2004 ; Bierer, 2007 ; Bierer and Faulkner, 2010 ; Bierer et al, 2015a , b ; Cosentino et al, 2016 ; Schvartz-Leyzac and Pfingst, 2016 ; Zhou, 2016 ; Mesnildrey et al, 2017 , 2019 ; Carlyon et al, 2018 ; DeVries and Arenberg, 2018 ; Guérit et al, 2018 ). A practical application of postoperative measures is deactivating a single or several electrodes in the array that result in improved outcomes in individual CI recipients ( Saleh et al, 2013 ; Bierer and Litvak, 2016 ; Vickers et al, 2016 ; Zhou, 2017 ); however, increasing the electrode number to more than 8 or 12 helps CI users to have a better perception even in a noisy environment ( Croghan et al, 2017 ; Schvartz-Leyzac et al, 2017 ).…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, several studies on human CI recipients reported different and contradictory outcomes by using polarity sensitivity ( Macherey et al, 2006 , 2017 ; Bahmer and Baumann, 2013 ; Karg et al, 2013 ; Undurraga et al, 2013 ; Hughes et al, 2017 , 2018 ; Mesnildrey et al, 2017 ; Luo J. et al, 2020 ; Xu et al, 2020 ). In addition, some studies suggested the variations of polarity sensitivity outcomes occurred not only between CI users but also between CI electrodes, sides of the ear, and cochlear turns ( Ranck, 1975 ; Macherey et al, 2017 ; Mesnildrey et al, 2017 ; Carlyon et al, 2018 ; Goehring et al, 2019 ; Jahn and Arenberg, 2019a , b ). As a consequence of conflicting results from recent investigations, polarity behavior depends on various factors and parameters that might differ in individual CI users.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Polarity Sensitivity of Human Auditory Nerve Fibers Based on Pulse Shape, Cochlear Implant Stimulation Strategy and Array

et al. 2021

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Neural health is of great interest to determine individual degeneration patterns for improving speech perception in cochlear implant (CI) users. Therefore, in recent years, several studies tried to identify and quantify neural survival in CI users. Among all proposed techniques, polarity sensitivity is a promising way to evaluate the neural status of auditory nerve fibers (ANFs) in CI users. Nevertheless, investigating neural health based on polarity sensitivity is a challenging and complicated task that involves various parameters, and the outcomes of many studies show contradictory results of polarity sensitivity behavior. Our computational study benefits from an accurate three-dimensional finite element model of a human cochlea with realistic human ANFs and determined ANF degeneration pattern of peripheral part with a diminishing of axon diameter and myelination thickness based on degeneration levels. In order to see how different parameters may impact the polarity sensitivity behavior of ANFs, we investigated polarity behavior under the application of symmetric and asymmetric pulse shapes, monopolar and multipolar CI stimulation strategies, and a perimodiolar and lateral CI array system. Our main findings are as follows: (1) action potential (AP) initiation sites occurred mainly in the peripheral site in the lateral system regardless of stimulation strategies, pulse polarities, pulse shapes, cochlear turns, and ANF degeneration levels. However, in the perimodiolar system, AP initiation sites varied between peripheral and central processes, depending on stimulation strategies, pulse shapes, and pulse polarities. (2) In perimodiolar array, clusters formed in threshold values based on cochlear turns and degeneration levels for multipolar strategies only when asymmetric pulses were applied. (3) In the perimodiolar array, a declining trend in polarity (anodic threshold/cathodic threshold) with multipolar strategies was observed between intact or slight degenerated cases and more severe degenerated cases, whereas in the lateral array, cathodic sensitivity was noticed for intact and less degenerated cases and anodic sensitivity for cases with high degrees of degeneration. Our results suggest that a combination of asymmetric pulse shapes, focusing more on multipolar stimulation strategies, as well as considering the distances to the modiolus wall, allows us to distinguish the degeneration patterns of ANFs across the cochlea.

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Section: Introductionmentioning

confidence: 87%

Section: Effect Of Pulse Shapementioning

confidence: 96%

Section: Effect Of Pulse Shapementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Polarity Sensitivity of Human Auditory Nerve Fibers Based on Pulse Shape, Cochlear Implant Stimulation Strategy and Array

et al. 2021

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Effects of Electrode Location on Estimates of Neural Health in Humans with Cochlear Implants

Schvartz-Leyzac

Holden

Zwolan

et al. 2020

JARO

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There are a number of psychophysical and electrophysiological measures that are correlated with SGN density in animal models, and these same measures can be performed in humans with cochlear implants (CIs). Thus, these measures are potentially applicable in humans for estimating the condition of the neural population (so called "neural health" or "cochlear health") at individual sites along the electrode array and possibly adjusting the stimulation strategy in the CI sound processor accordingly. Some measures used to estimate neural health in animals have included the electrically evoked compound potential (ECAP), psychophysical detection thresholds, and multipulse integration (MPI). With regard to ECAP measures, it has been shown that the change in the ECAP response as a function of increasing the stimulus interphase gap ("IPG Effect") also reflects neural density in implanted animals. These animal studies have typically been conducted using preparations in which the electrode was in a fixed position with respect to the neural population, whereas in human cochlear implant users, the position of individual electrodes varies widely within an electrode array and also across subjects. The current study evaluated the effects of electrode location in the implanted cochlea (specifically medial-lateral location) on various electrophysiological and psychophysical measures in eleven human subjects. The results demonstrated that some measures of interest, specifically ECAP thresholds, psychophysical detection thresholds, and ECAP amplitude-growth function (AGF) linear slope, were significantly related to the distances between the electrode and mid-modiolar axis (MMA). These same measures were less strongly related or not significantly related to the electrode to medial wall (MW) distance. In contrast, neither the IPG Effect for the ECAP AGF slope or threshold, nor the MPI slopes were significantly related to MMA or MW distance from the electrodes. These results suggest that "within-channel" estimates of neural health such as the IPG Effect and MPI slope might be more suitable for estimating nerve condition in humans for clinical application since they appear to be relatively independent of electrode position.

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Personalizing Transient Noise Reduction Algorithm Settings for Cochlear Implant Users

et al. 2021

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Objectives: Speech understanding in noise is difficult for patients with a cochlear implant. One common and disruptive type of noise is transient noise. We have tested transient noise reduction (TNR) algorithms in cochlear implant users to investigate the merits of personalizing the noise reduction settings based on a subject’s own preference. Design: The effect of personalizing two parameters of a broadband and a multiband TNR algorithm (TNR bb and TNR mb , respectively) on speech recognition was tested in a group of 15 unilaterally implanted subjects in cafeteria noise. The noise consisted of a combination of clattering dishes and babble noise. Each participant could individually vary two parameters, namely the scaling factor of the attenuation and the release time (τ). The parameter τ represents the duration of the attenuation applied after a transient is detected. As a reference, the current clinical standard TNR “SoundRelax” from Advanced Bionics was tested (TNR bb-std ). Effectiveness of the algorithms on speech recognition was evaluated adaptively by determining the speech reception threshold (SRT). Possible subjective benefits of the algorithms were assessed using a rating task at a fixed signal-to-noise ratio (SNR) of SRT + 3 dB. Rating was performed on four items, namely speech intelligibility, speech naturalness, listening effort, and annoyance of the noise. Word correct scores were determined at these fixed speech levels as well. Results: The personalized TNR mb improved the SRT statistically significantly with 1.3 dB, while the personalized TNR bb degraded it significantly by 1.7 dB. For TNR mb , we attempted to further optimize its settings by determining a group-based setting, leaving out those subjects that did not experience a benefit from it. Using these group-based settings, however, TNR mb did not have a significant effect on the SRT any longer. TNR bb-std did not affect speech recognition significantly. No significant effects on subjective ratings were found for any of the items investigated. In addition, at a constant speech level of SRT + 3 dB, no effect of any of the algorithms was found on word correct scores, including TNR mb with personalized settings. Conclusions: Our study results indicate that personalizing noise reduction settings of a multiband TNR algorithm can significantly improve speech intelligibility in transient noise, but only under challenging listening conditions around the SRT. At more favorable SNRs (SRT + 3 dB), this benefit was lost. We hypothesize that TNR mb was beneficial at lower SNRs, because of more effective artifact detection under those conditions. Group-averaged settings of the multiband al...

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Effect of stimulus polarity on detection thresholds in cochlear implant users: relationships with average threshold, gap detection, and rate discrimination

Cited by 4 publications

References 43 publications

Polarity Sensitivity of Human Auditory Nerve Fibers Based on Pulse Shape, Cochlear Implant Stimulation Strategy and Array

Polarity Sensitivity of Human Auditory Nerve Fibers Based on Pulse Shape, Cochlear Implant Stimulation Strategy and Array

Effects of Electrode Location on Estimates of Neural Health in Humans with Cochlear Implants

Personalizing Transient Noise Reduction Algorithm Settings for Cochlear Implant Users

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