Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners

Langner, Florian; Büchner, Andreas; Nogueira, Waldo

doi:10.1177/2331216520970349

Cited by 6 publications

(5 citation statements)

References 33 publications

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“…The back-end compressor (Langer et al, 2020) in the Crystalis XDP sound coding strategy called Voice Guard (VG) consists of four-bands with fixed knee points where the compression function of each band can be separately adjusted. Input dynamic range (IDR) refers to sound intensities between the softest and loudest sounds that can be captured by the microphone for further processing and it is by default set to 70 dB.…”

Section: Methodsmentioning

confidence: 99%

“…Percentile analysis is a useful tool to characterize the dynamics of a certain quantity and has been used to characterize the DR of hearing aid and CI compressors (Kirchberger & Russo, 2016; Langer et al, 2020; Ma et al 2015; Moore, 2008). Values in a set of samples that are greater than a specific percentage of all samples are called percentiles and are used in DR calculation.…”

Section: Methodsmentioning

confidence: 99%

“…Finally, the back-end compressor in the CI sound coding strategy may be used to optimize the EDR for singing music. Most compression systems used in CIs are designed and optimized for speech and in particular for speech in quiet (Langner et al, 2020). Therefore, designing a back-end compressor for music in the CI sound coding to improve music appreciation may be needed (Moore & Se ̨k, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Optimization of Sound Coding Strategies to Make Singing Music More Accessible for Cochlear Implant Users

2023

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Cochlear implants (CIs) are implantable medical devices that can partially restore hearing to people suffering from profound sensorineural hearing loss. While these devices provide good speech understanding in quiet, many CI users face difficulties when listening to music. Reasons include poor spatial specificity of electric stimulation, limited transmission of spectral and temporal fine structure of acoustic signals, and restrictions in the dynamic range that can be conveyed via electric stimulation of the auditory nerve. The coding strategies currently used in CIs are typically designed for speech rather than music. This work investigates the optimization of CI coding strategies to make singing music more accessible to CI users. The aim is to reduce the spectral complexity of music by selecting fewer bands for stimulation, attenuating the background instruments by strengthening a noise reduction algorithm, and optimizing the electric dynamic range through a back-end compressor. The optimizations were evaluated through both objective and perceptual measures of speech understanding and melody identification of singing voice with and without background instruments, as well as music appreciation questionnaires. Consistent with the objective measures, results gathered from the perceptual evaluations indicated that reducing the number of selected bands and optimizing the electric dynamic range significantly improved speech understanding in music. Moreover, results obtained from questionnaires show that the new music back-end compressor significantly improved music enjoyment. These results have potential as a new CI program for improved singing music perception.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Optimization of Sound Coding Strategies to Make Singing Music More Accessible for Cochlear Implant Users

2023

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“…One manufacturer of CIs, Oticon Medical, uses a different system, which is illustrated in Figure 4 , adapted from Langner et al (2020) . This system does not use a front-end AGC.…”

Section: Squeezing Music Into the Limited Dynamic Range Of The CI Usermentioning

confidence: 99%

Listening to Music Through Hearing Aids: Potential Lessons for Cochlear Implants

Moore

2022

Trends in Hearing

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Some of the problems experienced by users of hearing aids (HAs) when listening to music are relevant to cochlear implants (CIs). One problem is related to the high peak levels (up to 120 dB SPL) that occur in live music. Some HAs and CIs overload at such levels, because of the limited dynamic range of the microphones and analogue-to-digital converters (ADCs), leading to perceived distortion. Potential solutions are to use 24-bit ADCs or to include an adjustable gain between the microphones and the ADCs. A related problem is how to squeeze the wide dynamic range of music into the limited dynamic range of the user, which can be only 6–20 dB for CI users. In HAs, this is usually done via multi-channel amplitude compression (automatic gain control, AGC). In CIs, a single-channel front-end AGC is applied to the broadband input signal or a control signal derived from a running average of the broadband signal level is used to control the mapping of the channel envelope magnitude to an electrical signal. This introduces several problems: (1) an intense narrowband signal (e.g. a strong bass sound) reduces the level for all frequency components, making some parts of the music harder to hear; (2) the AGC introduces cross-modulation effects that can make a steady sound (e.g. sustained strings or a sung note) appear to fluctuate in level. Potential solutions are to use several frequency channels to create slowly varying gain-control signals and to use slow-acting (or dual time-constant) AGC rather than fast-acting AGC.

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“…Electric stimulation has its limitations to convey the necessary information for the proper coding of sounds in the auditory system (Moore, 2003 ). To reduce this gap, researchers are dedicated to find better CI sound coding strategies (Nogueira et al, 2005 , 2009 ; Landsberger and Srinivasan, 2009 ; Dillon et al, 2016 ; Langner et al, 2020a ; Gajecki and Nogueira, 2021 ), but the evaluation of the potential benefits of new ideas usually requires extensive testing procedures with implanted volunteers. In addition, there is high variability in the performance among CI users (Moberly et al, 2016 ), which makes it more difficult to generalize from the results.…”

Section: Introductionmentioning

confidence: 99%

A computational model to simulate spectral modulation and speech perception experiments of cochlear implant users

Alvarez

Kipping²,

Nogueira³

2023

Front. Neuroinform.

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Speech understanding in cochlear implant (CI) users presents large intersubject variability that may be related to different aspects of the peripheral auditory system, such as the electrode–nerve interface and neural health conditions. This variability makes it more challenging to proof differences in performance between different CI sound coding strategies in regular clinical studies, nevertheless, computational models can be helpful to assess the speech performance of CI users in an environment where all these physiological aspects can be controlled. In this study, differences in performance between three variants of the HiRes Fidelity 120 (F120) sound coding strategy are studied with a computational model. The computational model consists of (i) a processing stage with the sound coding strategy, (ii) a three-dimensional electrode-nerve interface that accounts for auditory nerve fiber (ANF) degeneration, (iii) a population of phenomenological ANF models, and (iv) a feature extractor algorithm to obtain the internal representation (IR) of the neural activity. As the back-end, the simulation framework for auditory discrimination experiments (FADE) was chosen. Two experiments relevant to speech understanding were performed: one related to spectral modulation threshold (SMT), and the other one related to speech reception threshold (SRT). These experiments included three different neural health conditions (healthy ANFs, and moderate and severe ANF degeneration). The F120 was configured to use sequential stimulation (F120-S), and simultaneous stimulation with two (F120-P) and three (F120-T) simultaneously active channels. Simultaneous stimulation causes electric interaction that smears the spectrotemporal information transmitted to the ANFs, and it has been hypothesized to lead to even worse information transmission in poor neural health conditions. In general, worse neural health conditions led to worse predicted performance; nevertheless, the detriment was small compared to clinical data. Results in SRT experiments indicated that performance with simultaneous stimulation, especially F120-T, were more affected by neural degeneration than with sequential stimulation. Results in SMT experiments showed no significant difference in performance. Although the proposed model in its current state is able to perform SMT and SRT experiments, it is not reliable to predict real CI users' performance yet. Nevertheless, improvements related to the ANF model, feature extraction, and predictor algorithm are discussed.

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Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners

Cited by 6 publications

References 33 publications

Optimization of Sound Coding Strategies to Make Singing Music More Accessible for Cochlear Implant Users

Optimization of Sound Coding Strategies to Make Singing Music More Accessible for Cochlear Implant Users

Listening to Music Through Hearing Aids: Potential Lessons for Cochlear Implants

A computational model to simulate spectral modulation and speech perception experiments of cochlear implant users

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