Perception and prediction of loudness in sound coding strategies using simultaneous electric stimulation

Langner, Florian; McKay, Colette M.; Büchner, Andreas; Nogueira, Waldo

doi:10.1016/j.heares.2020.108091

Cited by 4 publications

(9 citation statements)

References 23 publications

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“…Nevertheless, stimulation strategies could also be used to achieve some savings in power consumption. Some previous studies have shown that Paired stimulation reduces average stimulating current by 20% and Triplet by 45% ( Langner et al., 2017 , 2020 ).…”

Section: Methodsmentioning

confidence: 97%

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Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users

et al. 2021

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Speech intelligibility in multitalker settings is challenging for most cochlear implant (CI) users. One possibility for this limitation is the suboptimal representation of vocal cues in implant processing, such as the fundamental frequency (F0), and the vocal tract length (VTL). Previous studies suggested that while F0 perception depends on spectrotemporal cues, VTL perception relies largely on spectral cues. To investigate how spectral smearing in CIs affects vocal cue perception in speech-on-speech (SoS) settings, adjacent electrodes were simultaneously stimulated using current steering in 12 Advanced Bionics users to simulate channel interaction. In current steering, two adjacent electrodes are simultaneously stimulated forming a channel of parallel stimulation. Three such stimulation patterns were used: Sequential (one current steering channel), Paired (two channels), and Triplet stimulation (three channels). F0 and VTL just-noticeable differences (JNDs; Task 1), in addition to SoS intelligibility (Task 2) and comprehension (Task 3), were measured for each stimulation strategy. In Tasks 2 and 3, four maskers were used: the same female talker, a male voice obtained by manipulating both F0 and VTL (F0+VTL) of the original female speaker, a voice where only F0 was manipulated, and a voice where only VTL was manipulated. JNDs were measured relative to the original voice for the F0, VTL, and F0+VTL manipulations. When spectral smearing was increased from Sequential to Triplet, a significant deterioration in performance was observed for Tasks 1 and 2, with no differences between Sequential and Paired stimulation. Data from Task 3 were inconclusive. These results imply that CI users may tolerate certain amounts of channel interaction without significant reduction in performance on tasks relying on voice perception. This points to possibilities for using parallel stimulation in CIs for reducing power consumption.

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Section: Methodsmentioning

confidence: 97%

“…(2017) . This is mainly due to the electrical interactions between the simultaneously stimulating channels, decreasing the necessary current required to achieve the same loudness percept ( Langner et al., 2020 ). These interactions depend on the number of stimulating channels and the distance between them.…”

Section: Methodsmentioning

confidence: 99%

Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users

et al. 2021

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“…In the case of stimuli with simultaneous biphasic pulses, the Practical Method could still be used if psychophysical loudness summation data due to current summation for the stimulus conditions used (e.g., mode of stimulation and electrode distance) were obtained and included in the model. An example of such an adaptation of the Practical Method was demonstrated by Langner et al (2020), who measured loudness summation caused by current interaction of simultaneously activated pairs of virtual channels. Virtual channels simultaneously activate two adjacent intracochlear electrodes to steer the peak of the current field to positions between the physical electrodes.…”

Section: Extensions Of the Practical Methodsmentioning

confidence: 99%

“…Such paired virtual channels are used in the "Optima-Paired" sound coding strategy of Advanced Bionics. In the adaption of the Practical Method, Langner et al (2020) balanced the loudness of paired-channel stimuli to those of the component single virtual channels to create a model of how channel distance, and relative currents in the component channels of each pair, influence the loudness. This additional model was then incorporated into the Practical Method to predict the loudness of paired-channel stimulation strategies compared to strategies that sequentially activated virtual channels.…”

Section: Extensions Of the Practical Methodsmentioning

confidence: 99%

“…To do this prediction, the loudness contribution of each paired-channel pulse pair was replaced in the Practical Method calculation of the loudness by an equivalently loud single-channel pulse with current determined by the model derived from loudness balancing data. This method of Langner et al (2020) provides a way for clinicians to automatically adjust the program of the sound processors when switching between paired-pulse and fully sequential signal processing strategies. To do this adjustment when changing to the paired strategy from a sequential strategy, clinicians can lower the current range assigned to each virtual electrode (which is determined for sequential stimulation using each virtual channel separately) by an amount predicted by the model calculation, so that the simultaneous stimulation does not produce sounds that are too loud.…”

Section: Extensions Of the Practical Methodsmentioning

confidence: 99%

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Applications of Phenomenological Loudness Models to Cochlear Implants

McKay

2021

Front. Psychol.

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Cochlear implants electrically stimulate surviving auditory neurons in the cochlea to provide severely or profoundly deaf people with access to hearing. Signal processing strategies derive frequency-specific information from the acoustic signal and code amplitude changes in frequency bands onto amplitude changes of current pulses emitted by the tonotopically arranged intracochlear electrodes. This article first describes how parameters of the electrical stimulation influence the loudness evoked and then summarizes two different phenomenological models developed by McKay and colleagues that have been used to explain psychophysical effects of stimulus parameters on loudness, detection, and modulation detection. The Temporal Model is applied to single-electrode stimuli and integrates cochlear neural excitation using a central temporal integration window analogous to that used in models of normal hearing. Perceptual decisions are made using decision criteria applied to the output of the integrator. By fitting the model parameters to a variety of psychophysical data, inferences can be made about how electrical stimulus parameters influence neural excitation in the cochlea. The Detailed Model is applied to multi-electrode stimuli, and includes effects of electrode interaction at a cochlear level and a transform between integrated excitation and specific loudness. The Practical Method of loudness estimation is a simplification of the Detailed Model and can be used to estimate the relative loudness of any multi-electrode pulsatile stimuli without the need to model excitation at the cochlear level. Clinical applications of these models to novel sound processing strategies are described.

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Assessing the relationship between neural health measures and speech performance with simultaneous electric stimulation in cochlear implant listeners

et al. 2021

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Objectives The relationship between electrode-nerve interface (ENI) estimates and inter-subject differences in speech performance with sequential and simultaneous channel stimulation in adult cochlear implant listeners were explored. We investigated the hypothesis that individuals with good ENIs would perform better with simultaneous compared to sequential channel stimulation speech processing strategies than those estimated to have poor ENIs. Methods Fourteen postlingually deaf implanted cochlear implant users participated in the study. Speech understanding was assessed with a sentence test at signal-to-noise ratios that resulted in 50% performance for each user with the baseline strategy F120 Sequential. Two simultaneous stimulation strategies with either two (Paired) or three sets of virtual channels (Triplet) were tested at the same signal-to-noise ratio. ENI measures were estimated through: (I) voltage spread with electrical field imaging, (II) behavioral detection thresholds with focused stimulation, and (III) slope (IPG slope effect) and 50%-point differences (dB offset effect) of amplitude growth functions from electrically evoked compound action potentials with two interphase gaps. Results A significant effect of strategy on speech understanding performance was found, with Triplets showing a trend towards worse speech understanding performance than sequential stimulation. Focused thresholds correlated positively with the difference required to reach most comfortable level (MCL) between Sequential and Triplet strategies, an indirect measure of channel interaction. A significant offset effect (difference in dB between 50%-point for higher eCAP growth function slopes with two IPGs) was observed. No significant correlation was observed between the slopes for the two IPGs tested. None of the measures used in this study correlated with the differences in speech understanding scores between strategies. Conclusions The ENI measure based on behavioral focused thresholds could explain some of the difference in MCLs, but none of the ENI measures could explain the decrease in speech understanding with increasing pairs of simultaneously stimulated electrodes in processing strategies.

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Perception and prediction of loudness in sound coding strategies using simultaneous electric stimulation

Cited by 4 publications

References 23 publications

Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users

Effect of Channel Interaction on Vocal Cue Perception in Cochlear Implant Users

Applications of Phenomenological Loudness Models to Cochlear Implants

Assessing the relationship between neural health measures and speech performance with simultaneous electric stimulation in cochlear implant listeners

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