Reducing Simulated Channel Interaction Reveals Differences in Phoneme Identification Between Children and Adults With Normal Hearing

Jahn, Kelly N.; DiNino, Mishaela; Arenberg, Julie G.

doi:10.1097/aud.0000000000000615

Cited by 23 publications

(23 citation statements)

References 84 publications

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“…Further, although the relation between spectral discrimination and speech identification scores in pediatric CI users may depend on the tests utilized (e.g., DiNino & Arenberg, 2018; Gifford et al 2018), current interaction between channels could be more problematic for children if they do indeed have greater neuronal densities (Jahn et al 2018). Children could potentially benefit from processing strategies that use focused electrode configurations to reduce this channel interaction, which have had only minimal success in some adults (Berenstein et al 2008; Srinivasan et al 2013).…”

Section: Discussionmentioning

confidence: 99%

The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults

DiNino

O’Brien

Bierer

et al. 2019

JARO

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Cochlear implant (CI) programming is similar for all CI users despite limited understanding of the electrode-neuron interface (ENI). The ENI refers to the ability of each CI electrode to effectively stimulate target auditory neurons and is influenced by electrode position, neural health, cochlear geometry, and bone and tissue growth in the cochlea. Hearing history likely affects these variables, suggesting that the efficacy of each channel of stimulation differs between children who were implanted at young ages and adults who lost hearing and received a CI later in life. This study examined whether ENI quality differed between early-implanted children and late-implanted adults. Auditory detection thresholds and most comfortable levels (MCLs) were obtained with monopolar and focused electrode configurations. Channel-to-channel variability and dynamic range were calculated for both types of stimulation. Electrical field imaging data were also acquired to estimate levels of intracochlear resistance. Children exhibited lower average auditory perception thresholds and MCLs compared with adults, particularly with focused stimulation. However, neither dynamic range nor channel-to-channel threshold variability differed between groups, suggesting that children’s range of perceptible current was shifted downward. Children also demonstrated increased intracochlear resistance levels relative to the adult group, possibly reflecting greater ossification or tissue growth after CI surgery. These results illustrate physical and perceptual differences related to the ENI of early-implanted children compared with late-implanted adults. Evidence from this study demonstrates a need for further investigation of the ENI in CI users with varying hearing histories.

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Section: Discussionmentioning

confidence: 99%

The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults

DiNino

O’Brien

Bierer

et al. 2019

JARO

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“…Previous studies have used normal-hearing (NH) listeners and noise- or tone-based envelope vocoder schemes to simulate the effects of current spread by varying the spectral overlap between channels and/or by changing the total number of channels (Qin and Oxenham 2003 ; Fu and Nogaki 2005 ; Litvak et al 2007 ; Bingabr et al 2008 ; Crew and Galvin 2012 ; Oxenham and Kreft 2014 ; Mesnildrey and Macherey 2015 ; Grange et al 2017 ; Jahn et al 2019 ). In those studies, spectral overlap between channels with slopes of about − 12 dB/octave and about 4–8 channels led to similar results between speech-in-noise performances by NH listeners using vocoders and CI users.…”

Section: Introductionmentioning

confidence: 99%

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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“…For example, In Gaudrain and Baskent (2018), the recognition of a shift in the spectral envelope of a syllable significantly changed at −24 dB/octave compared to −48 and −72 dB/octave filter slopes [ 55 ]. In Jahn et al (2019) vowel and consonant recognition dropped significantly for −15 dB/octave filter slopes compared to −30 and −60 dB/octave conditions [ 34 ]. This threshold effect may be due to the smaller difference of slope between −48 and −72 dB/octave filters than between −24 and −48 dB/octave filters.…”

Section: Discussionmentioning

confidence: 99%

“…After channel selection, temporal envelopes were reconstructed by modulating Hamming windows with the RMS-amplitudes and by using an “overlap-and-add” procedure (75% overlap). A second-order Butterworth filter with a 65-Hz cutoff frequency (half the gap between the frequency bins) was used to smooth the envelopes [ 33 , 34 , 35 ]. Then, the temporal envelopes were used to modulate narrowband noises with the same cutoff frequencies as the corresponding analysis channels ( Table 1 ).…”

Section: Methodsmentioning

confidence: 99%

Word Recognition and Frequency Selectivity in Cochlear Implant Simulation: Effect of Channel Interaction

Cucis

Berger‐Vachon

Thai‐Van

et al. 2021

JCM

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In cochlear implants (CI), spread of neural excitation may produce channel interaction. Channel interaction disturbs the spectral resolution and, among other factors, seems to impair speech recognition, especially in noise. In this study, two tests were performed with 20 adult normal-hearing (NH) subjects under different vocoded simulations. First, there was a measurement of word recognition in noise while varying the number of selected channels (4, 8, 12 or 16 maxima out of 20) and the degree of simulated channel interaction (“Low”, “Medium” and “High”). Then, there was an evaluation of spectral resolution function of the degree of simulated channel interaction, reflected by the sharpness (Q10dB) of psychophysical tuning curves (PTCs). The results showed a significant effect of the simulated channel interaction on word recognition but did not find an effect of the number of selected channels. The intelligibility decreased significantly for the highest degree of channel interaction. Similarly, the highest simulated channel interaction impaired significantly the Q10dB. Additionally, a strong intra-individual correlation between frequency selectivity and word recognition in noise was observed. Lastly, the individual changes in frequency selectivity were positively correlated with the changes in word recognition when the degree of interaction went from “Low” to “High”. To conclude, the degradation seen for the highest degree of channel interaction suggests a threshold effect on frequency selectivity and word recognition. The correlation between frequency selectivity and intelligibility in noise supports the hypothesis that PTCs Q10dB can account for word recognition in certain conditions. Moreover, the individual variations of performances observed among subjects suggest that channel interaction does not have the same effect on each individual. Finally, these results highlight the importance of taking into account subjects’ individuality and to evaluate channel interaction through the speech processor.

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Reducing Simulated Channel Interaction Reveals Differences in Phoneme Identification Between Children and Adults With Normal Hearing

Cited by 23 publications

References 84 publications

The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults

The Estimated Electrode-Neuron Interface in Cochlear Implant Listeners Is Different for Early-Implanted Children and Late-Implanted Adults

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

Word Recognition and Frequency Selectivity in Cochlear Implant Simulation: Effect of Channel Interaction

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