Improved fundamental frequency coding in cochlear implant signal processing

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.

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Effects of Signal Processing by the House-3M Cochlear Implant on Consonant Perception

Acta Oto-Laryngologica ◽

10.3109/00016488409121681 ◽

1984 ◽

Vol 97 (sup413) ◽

pp. 115-123 ◽

Cited By ~ 3

Author(s):

Bradly J. Edgerton ◽

Judith A. Brimacombe

Keyword(s):

Signal Processing ◽

Cochlear Implant

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Evaluation of an Adaptive Dynamic Compensation System in Cochlear Implant Listeners

Trends in Hearing ◽

10.1177/2331216520970349 ◽

2020 ◽

Vol 24 ◽

pp. 233121652097034

Author(s):

Florian Langner ◽

Andreas Büchner ◽

Waldo Nogueira

Keyword(s):

Signal Processing ◽

Cochlear Implant ◽

Speech Intelligibility ◽

Discrimination Task ◽

Signal To Noise Ratio ◽

Compensation System ◽

Signal To Noise ◽

Dynamic Compensation ◽

Front End ◽

Noise Ratio

Cochlear implant (CI) sound processing typically uses a front-end automatic gain control (AGC), reducing the acoustic dynamic range (DR) to control the output level and protect the signal processing against large amplitude changes. It can also introduce distortions into the signal and does not allow a direct mapping between acoustic input and electric output. For speech in noise, a reduction in DR can result in lower speech intelligibility due to compressed modulations of speech. This study proposes to implement a CI signal processing scheme consisting of a full acoustic DR with adaptive properties to improve the signal-to-noise ratio and overall speech intelligibility. Measurements based on the Short-Time Objective Intelligibility measure and an electrodogram analysis, as well as behavioral tests in up to 10 CI users, were used to compare performance with a single-channel, dual-loop, front-end AGC and with an adaptive back-end multiband dynamic compensation system (Voice Guard [VG]). Speech intelligibility in quiet and at a +10 dB signal-to-noise ratio was assessed with the Hochmair–Schulz–Moser sentence test. A logatome discrimination task with different consonants was performed in quiet. Speech intelligibility was significantly higher in quiet for VG than for AGC, but intelligibility was similar in noise. Participants obtained significantly better scores with VG than AGC in the logatome discrimination task. The objective measurements predicted significantly better performance estimates for VG. Overall, a dynamic compensation system can outperform a single-stage compression (AGC + linear compression) for speech perception in quiet.

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Saliency of Vowel Features in Neural Responses of Cochlear Implant Users

Clinical EEG and Neuroscience ◽

10.1177/1550059418770051 ◽

2018 ◽

Vol 49 (6) ◽

pp. 388-397

Author(s):

François Prévost ◽

Alexandre Lehmann

Keyword(s):

Speech Recognition ◽

Cochlear Implant ◽

Fundamental Frequency ◽

Mismatch Negativity ◽

Free Field ◽

Event Related Potentials ◽

Oddball Paradigm ◽

Aural Rehabilitation ◽

Spectral Components ◽

Related Potentials

Cochlear implants restore hearing in deaf individuals, but speech perception remains challenging. Poor discrimination of spectral components is thought to account for limitations of speech recognition in cochlear implant users. We investigated how combined variations of spectral components along two orthogonal dimensions can maximize neural discrimination between two vowels, as measured by mismatch negativity. Adult cochlear implant users and matched normal-hearing listeners underwent electroencephalographic event-related potentials recordings in an optimum-1 oddball paradigm. A standard /a/ vowel was delivered in an acoustic free field along with stimuli having a deviant fundamental frequency (+3 and +6 semitones), a deviant first formant making it a /i/ vowel or combined deviant fundamental frequency and first formant (+3 and +6 semitones /i/ vowels). Speech recognition was assessed with a word repetition task. An analysis of variance between both amplitude and latency of mismatch negativity elicited by each deviant vowel was performed. The strength of correlations between these parameters of mismatch negativity and speech recognition as well as participants’ age was assessed. Amplitude of mismatch negativity was weaker in cochlear implant users but was maximized by variations of vowels’ first formant. Latency of mismatch negativity was later in cochlear implant users and was particularly extended by variations of the fundamental frequency. Speech recognition correlated with parameters of mismatch negativity elicited by the specific variation of the first formant. This nonlinear effect of acoustic parameters on neural discrimination of vowels has implications for implant processor programming and aural rehabilitation.

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The design and validation of a hybrid digital-signal-processing plug-in for traditional cochlear implant speech processors

Computer Methods and Programs in Biomedicine ◽

10.1016/j.cmpb.2018.03.003 ◽

2018 ◽

Vol 159 ◽

pp. 103-109 ◽

Cited By ~ 3

Author(s):

Fatemeh Hajiaghababa ◽

Hamid R. Marateb ◽

Saeed Kermani

Keyword(s):

Signal Processing ◽

Digital Signal Processing ◽

Cochlear Implant ◽

Digital Signal

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Evaluation of Automatic Directional Processing with Cochlear Implant Recipients

Journal of the American Academy of Audiology ◽

10.1055/s-0041-1733967 ◽

2021 ◽

Vol 32 (08) ◽

pp. 478-486

Author(s):

Lisa G. Potts ◽

Soo Jang ◽

Cory L. Hillis

Keyword(s):

Signal Processing ◽

Speech Recognition ◽

Cochlear Implant ◽

Mixed Model ◽

Dynamic Range ◽

Individual Variability ◽

Noise Performance ◽

Mixed Model Analysis ◽

Speech In Noise ◽

Speech Recognition In Noise

Abstract Background For cochlear implant (CI) recipients, speech recognition in noise is consistently poorer compared with recognition in quiet. Directional processing improves performance in noise and can be automatically activated based on acoustic scene analysis. The use of adaptive directionality with CI recipients is new and has not been investigated thoroughly, especially utilizing the recipients' preferred everyday signal processing, dynamic range, and/or noise reduction. Purpose This study utilized CI recipients' preferred everyday signal processing to evaluate four directional microphone options in a noisy environment to determine which option provides the best speech recognition in noise. A greater understanding of automatic directionality could ultimately improve CI recipients' speech-in-noise performance and better guide clinicians in programming. Study Sample Twenty-six unilateral and seven bilateral CI recipients with a mean age of 66 years and approximately 4 years of CI experience were included. Data Collection and Analysis Speech-in-noise performance was measured using eight loudspeakers in a 360-degree array with HINT sentences presented in restaurant noise. Four directional options were evaluated (automatic [SCAN], adaptive [Beam], fixed [Zoom], and Omni-directional) with participants' everyday use signal processing options active. A mixed-model analysis of variance (ANOVA) and pairwise comparisons were performed. Results Automatic directionality (SCAN) resulted in the best speech-in-noise performance, although not significantly better than Beam. Omni-directional performance was significantly poorer compared with the three other directional options. A varied number of participants performed their best with each of the four-directional options, with 16 performing best with automatic directionality. The majority of participants did not perform best with their everyday directional option. Conclusion The individual variability seen in this study suggests that CI recipients try with different directional options to find their ideal program. However, based on a CI recipient's motivation to try different programs, automatic directionality is an appropriate everyday processing option.

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