scholarly journals Evaluating Psychophysical Polarity Sensitivity as an Indirect Estimate of Neural Status in Cochlear Implant Listeners

2019 ◽  
Vol 20 (4) ◽  
pp. 415-430 ◽  
Author(s):  
Kelly N. Jahn ◽  
Julie G. Arenberg
Keyword(s):  
Cochlear Implant ◽  
Polarity Sensitivity

scholarly journals Polarity Sensitivity in Pediatric and Adult Cochlear Implant Listeners

2019 ◽  
Vol 23 ◽  
pp. 233121651986298 ◽  
Author(s):  
Kelly N. Jahn ◽  
Julie G. Arenberg
Keyword(s):  
Cochlear Implant ◽  
Dynamic Range ◽  
Single Channel ◽  
Spiral Ganglion ◽  
High Amplitude ◽  
Electrical Stimulus ◽  
Polarity Sensitivity ◽  
The Difference ◽  
Phoneme Perception ◽  
Ganglion Neurons

Modeling data suggest that sensitivity to the polarity of an electrical stimulus may reflect the integrity of the peripheral processes of the spiral ganglion neurons. Specifically, better sensitivity to anodic (positive) current than to cathodic (negative) current could indicate peripheral process degeneration or demyelination. The goal of this study was to characterize polarity sensitivity in pediatric and adult cochlear implant listeners (41 ears). Relationships between polarity sensitivity at threshold and (a) polarity sensitivity at suprathreshold levels, (b) age-group, (c) preimplantation duration of deafness, and (d) phoneme perception were determined. Polarity sensitivity at threshold was defined as the difference in single-channel behavioral thresholds measured in response to each of two triphasic pulses, where the central high-amplitude phase was either cathodic or anodic. Lower thresholds in response to anodic than to cathodic pulses may suggest peripheral process degeneration. On the majority of electrodes tested, threshold and suprathreshold sensitivity was lower for anodic than for cathodic stimulation; however, dynamic range was often larger for cathodic than for anodic stimulation. Polarity sensitivity did not differ between child- and adult-implanted listeners. Adults with long preimplantation durations of deafness tended to have better sensitivity to anodic pulses on channels that were estimated to interface poorly with the auditory nerve; this was not observed in the child-implanted group. Across subjects, duration of deafness predicted phoneme perception performance. The results of this study suggest that subject- and electrode-dependent differences in polarity sensitivity may assist in developing customized cochlear implant programming interventions for child- and adult-implanted listeners.

scholarly journals Polarity Sensitivity as a Potential Correlate of Neural Degeneration in Cochlear Implant Users

2020 ◽  
Vol 21 (1) ◽  
pp. 89-104 ◽  
Author(s):  
Quentin Mesnildrey ◽  
Frédéric Venail ◽  
Robert P. Carlyon ◽  
Olivier Macherey
Keyword(s):  
Cochlear Implant ◽  
Neural Degeneration ◽  
Polarity Sensitivity

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

2021 ◽  
Vol 15 ◽  
Author(s):  
Amirreza Heshmat ◽  
Sogand Sajedi ◽  
Anneliese Schrott-Fischer ◽  
Frank Rattay
Keyword(s):  
Cochlear Implant ◽  
Auditory Nerve ◽  
Computational Study ◽  
Three Dimensional ◽  
Element Model ◽  
Nerve Fibers ◽  
Polarity Sensitivity ◽  
Auditory Nerve Fibers ◽  
Asymmetric Pulse ◽  
Peripheral Site

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.

Letter to the Editor Concerning Skuk et al., “Parameter-Specific Morphing Reveals Contributions of Timbre and Fundamental Frequency Cues to the Perception of Voice Gender and Age in Cochlear Implant Users”

2020 ◽  
Vol 63 (12) ◽  
pp. 4325-4326 ◽  
Author(s):  
Hartmut Meister ◽  
Katrin Fuersen ◽  
Barbara Streicher ◽  
Ruth Lang-Roth ◽  
Martin Walger
Keyword(s):  
Cochlear Implant ◽  
Fundamental Frequency ◽  
Stimulus Type ◽  
Voice Perception ◽  
Letter To The Editor ◽  
Gender And Age ◽  
General Influence

Purpose The purpose of this letter is to compare results by Skuk et al. (2020) with Meister et al. (2016) and to point to a potential general influence of stimulus type. Conclusion Our conclusion is that presenting sentences may give cochlear implant recipients the opportunity to use timbre cues for voice perception. This might not be the case when presenting brief and sparse stimuli such as consonant–vowel–consonant or single words, which were applied in the majority of studies.

Perceptual Learning of Vocoded Speech With and Without Contralateral Hearing: Implications for Cochlear Implant Rehabilitation

2020 ◽  
pp. 1-10
Author(s):  
Martin Chavant ◽  
Alexis Hervais-Adelman ◽  
Olivier Macherey
Keyword(s):  
Cochlear Implant ◽  
Perceptual Learning ◽  
Speech Signal ◽  
Training Phase ◽  
Monosyllabic Words ◽  
Low Pass ◽  
Contralateral Ear ◽  
Number Of Individuals ◽  
Insight Into ◽  
Vocoded Speech

Purpose An increasing number of individuals with residual or even normal contralateral hearing are being considered for cochlear implantation. It remains unknown whether the presence of contralateral hearing is beneficial or detrimental to their perceptual learning of cochlear implant (CI)–processed speech. The aim of this experiment was to provide a first insight into this question using acoustic simulations of CI processing. Method Sixty normal-hearing listeners took part in an auditory perceptual learning experiment. Each subject was randomly assigned to one of three groups of 20 referred to as NORMAL, LOWPASS, and NOTHING. The experiment consisted of two test phases separated by a training phase. In the test phases, all subjects were tested on recognition of monosyllabic words passed through a six-channel “PSHC” vocoder presented to a single ear. In the training phase, which consisted of listening to a 25-min audio book, all subjects were also presented with the same vocoded speech in one ear but the signal they received in their other ear differed across groups. The NORMAL group was presented with the unprocessed speech signal, the LOWPASS group with a low-pass filtered version of the speech signal, and the NOTHING group with no sound at all. Results The improvement in speech scores following training was significantly smaller for the NORMAL than for the LOWPASS and NOTHING groups. Conclusions This study suggests that the presentation of normal speech in the contralateral ear reduces or slows down perceptual learning of vocoded speech but that an unintelligible low-pass filtered contralateral signal does not have this effect. Potential implications for the rehabilitation of CI patients with partial or full contralateral hearing are discussed.

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