ECAP spread of excitation with virtual channels and physical electrodes

Hughes, Michelle L.; Stille, Lisa J.; Baudhuin, Jacquelyn L.; Goehring, Jenny L.

doi:10.1016/j.heares.2013.09.014

Cited by 24 publications

(42 citation statements)

References 22 publications

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“…To determine whether the ECAP spatial separation (R) itself was significantly different across electrode regions (basal, middle, or apical) a one-way RM-ANOVA was performed. Results revealed no significant main effect of electrode region (F[1,9] ¼ 0.83, p ¼ 0.39) on ECAP R, consistent with the larger data set previously reported by Hughes et al (2013). Figure 3 displays scatter plots of group mean pitchranking thresholds (a) versus ECAP separation indices (R) for basal, middle, and apical electrode regions (top to bottom, respectively).…”

Section: Pitch Ranking (A)supporting

confidence: 84%

“…More recently, Hughes and Goulson (2011) determined that virtual-channel SOE amplitudes fall approximately half-way between the amplitudes of adjacent physical electrodes for both dualelectrode mode and current steering. Hughes et al (2013) showed that spatial separation of SOE patterns was greater between adjacent physical electrodes than between the intermediate virtual channels and the flanking physical electrodes, indicating measurable separation between neural populations. Therefore, it seems conceivable that the ECAP SOE could be used as an objective tool to assist in predicting behavioral perception of virtual channels.…”

Section: Introductionmentioning

confidence: 95%

“…The ECAP SOE data for the 11 subjects in the present study represent a re-analysis of a subset of data from a larger physiological study (Hughes et al, 2013). Briefly, the traditional forward-masking subtraction procedure with a fixed probe and varied masker electrode (Abbas et al, 2004;Hughes and Abbas, 2006a,b) was used to obtain ECAP SOE functions.…”

Section: Ecap Stimuli and Proceduresmentioning

confidence: 99%

“…ECAP amplitudes were then normalized for each subject according to the highest amplitude across the two physical-electrode probe functions within a set and separately for each region. This was done to preserve the spatial relationships among the probe SOEs being compared and to allow for SOE comparisons across electrode sets and subjects (Hughes, 2008;Hughes and Goulson, 2011;Hughes et al, 2013). Following methodology from Hughes (2008), the amount of spatial separation (R) among each of the pairs of SOE functions was quantified.…”

Section: Ecap Stimuli and Proceduresmentioning

confidence: 99%

“…The ECAP SOE function has been examined for virtual-channel stimulation (Busby et al, 2008;Saoji et al, 2009;Hughes and Goulson, 2011;SnelBongers et al, 2012;Hughes et al, 2013). These studies have shown that virtual channels produce ECAP SOE patterns similar to those of physical electrodes.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

Goehring

Neff

Baudhuin

et al. 2014

The Journal of the Acoustical Society of America

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The first objective of this study was to determine whether adaptive pitch-ranking and electrodediscrimination tasks with cochlear-implant (CI) recipients produce similar results for perceiving intermediate "virtual-channel" pitch percepts using current steering. Previous studies have not examined both behavioral tasks in the same subjects with current steering. A second objective was to determine whether a physiological metric of spatial separation using the electrically evoked compound action potential spread-of-excitation (ECAP SOE) function could predict performance in the behavioral tasks. The metric was the separation index (R), defined as the difference in normalized amplitudes between two adjacent ECAP SOE functions, summed across all masker electrodes. Eleven CII or 90 K Advanced Bionics (Valencia, CA) recipients were tested using pairs of electrodes from the basal, middle, and apical portions of the electrode array. The behavioral results, expressed as d 0 , showed no significant differences across tasks. There was also no significant effect of electrode region for either task. ECAP R was not significantly correlated with pitch ranking or electrode discrimination for any of the electrode regions. Therefore, the ECAP separation index is not sensitive enough to predict perceptual resolution of virtual channels.

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Section: Pitch Ranking (A)supporting

confidence: 84%

Section: Introductionmentioning

confidence: 95%

Section: Ecap Stimuli and Proceduresmentioning

confidence: 99%

Section: Ecap Stimuli and Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

Goehring

Neff

Baudhuin

et al. 2014

The Journal of the Acoustical Society of America

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Using Spectral Blurring to Assess Effects of Channel Interaction on Speech-in-Noise Perception with Cochlear Implants

Goehring

Arenberg

Carlyon

2020

JARO

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Cochlear implant (CI) listeners struggle to understand speech in background noise. Interactions between electrode channels due to current spread increase the masking of speech by noise and lead to difficulties with speech perception. Strategies that reduce channel interaction therefore have the potential to improve speech-in-noise perception by CI listeners, but previous results have been mixed. We investigated the effects of channel interaction on speech-in-noise perception and its association with spectro-temporal acuity in a listening study with 12 experienced CI users. Instead of attempting to reduce channel interaction, we introduced spectral blurring to simulate some of the effects of channel interaction by adjusting the overlap between electrode channels at the input level of the analysis filters or at the output by using several simultaneously stimulated electrodes per channel. We measured speech reception thresholds in noise as a function of the amount of blurring applied to either all 15 electrode channels or to 5 evenly spaced channels. Performance remained roughly constant as the amount of blurring applied to all channels increased up to some knee point, above which it deteriorated. This knee point differed across listeners in a way that correlated with performance on a non-speech spectro-temporal task, and is proposed here as an individual measure of channel interaction. Surprisingly, even extreme amounts of blurring applied to 5 channels did not affect performance. The effects on speech perception in noise were similar for blurring at the input and at the output of the CI. The results are in line with the assumption that experienced CI users can make use of a limited number of effective channels of information and tolerate some deviations from their everyday settings when identifying speech in the presence of a masker. Furthermore, these findings may explain the mixed results by strategies that optimized or deactivated a small number of electrodes evenly distributed along the array by showing that blurring or deactivating one-third of the electrodes did not harm speech-in-noise performance.

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Loudness and pitch perception using Dynamically Compensated Virtual Channels

et al. 2017

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Reducing power consumption is important for the development of smaller cochlear implant (CI) speech processors. Simultaneous electrode stimulation may improve power efficiency by minimizing the required current applied to a given electrode. Simultaneous in-phase stimulation on adjacent electrodes (i.e. virtual channels) can be used to elicit pitch percepts intermediate to the ones provided by each of the physical electrodes in isolation. Virtual channels are typically implemented in monopolar stimulation mode, producing broad excitation patterns. Focused stimulation may reduce the excitation patterns, but is inefficient in terms of power consumption. To create a more power efficient virtual channel, we developed the Dynamically Compensated Virtual Channel (DC-VC) using four adjacent electrodes. The two central electrodes are current steered using the coefficient α (0 < α < 1) whereas the two flanking electrodes are used to focus/unfocus the stimulation with the coefficient σ(−1<σ<1). With increasing values of σ, power can be saved at the potential expense of generating broader electric fields. Additionally, reshaping the electric fields might also alter place pitch coding. The goal of the present study is to investigate the tradeoff between place pitch encoding and power savings using simultaneous electrode stimulation in the DC-VC configuration. A computational model and psychophysical experiments in CI users have been used for that purpose. Results from 10 adult Advanced Bionics CI users have been collected. Results show that the required current to produce comfortable levels is significantly reduced with increasing σ as predicted by the computational model. Moreover, no significant differences in the estimated number of discriminable steps were detected for the different values of σ. From these results, we conclude that DC-VCs can reduce power consumption without decreasing the number of discriminable place pitch steps.

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ECAP spread of excitation with virtual channels and physical electrodes

Cited by 24 publications

References 22 publications

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

Pitch ranking, electrode discrimination, and physiological spread of excitation using current steering in cochlear implants

Using Spectral Blurring to Assess Effects of Channel Interaction on Speech-in-Noise Perception with Cochlear Implants

Loudness and pitch perception using Dynamically Compensated Virtual Channels

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