Continuous Interleaved Sampling Strategy Research Articles

Open-Set Phoneme Recognition Performance With Varied Temporal Cues in Younger and Older Cochlear Implant Users.

The goal of this study was to investigate the effect of age on phoneme recognition performance in which the stimuli varied in the amount of temporal information available in the signal. Chronological age is increasingly recognized as a factor that can limit the amount of benefit an individual can receive from a cochlear implant (CI). Central auditory temporal processing deficits in older listeners may contribute to the performance gap between younger and older CI users on recognition of phonemes varying in temporal cues. Phoneme recognition was measured at three stimulation rates (500, 900, and 1800 pulses per second) and two envelope modulation frequencies (50 Hz and unfiltered) in 20 CI participants ranging in age from 27 to 85 years. Speech stimuli were multiple word pairs differing in temporal contrasts and were presented via direct stimulation of the electrode array using an eight-channel continuous interleaved sampling strategy. Phoneme recognition performance was evaluated at each stimulation rate condition using both envelope modulation frequencies. Duration of deafness was the strongest subject-level predictor of phoneme recognition, with participants with longer durations of deafness having poorer performance overall. Chronological age did not predict performance for any stimulus condition. Additionally, duration of deafness interacted with envelope filtering. Participants with shorter durations of deafness were able to take advantage of higher frequency envelope modulations, while participants with longer durations of deafness were not. Age did not significantly predict phoneme recognition performance. In contrast, longer durations of deafness were associated with a reduced ability to utilize available temporal information within the signal to improve phoneme recognition performance.

Signal processing & audio processors

Signal processing algorithms are the hidden components in the audio processor that converts the received acoustic signal into electrical impulses while maintaining as much relevant information as possible. Signal processing algorithms should be smart enough to mimic the functionality of external, middle and the inner-ear to provide the cochlear implant (CI) user with a hearing experience as natural as possible. Modern sound processing strategies are based on the continuous interleaved sampling (CIS) strategy proposed by B. Wilson in 1991, which provided envelope information over several intracochlear electrodes. The CIS strategy brought significant gains in speech perception. Translational research activities of MED-EL resulted in further improvements in speech understanding in noisy environments as well as enjoyment of music by not only coding CIS-based envelope information, but by also representing temporal fine structure information in the stimulation patterns of the apical channels. Further developments include “complete cochlear coverage” made possible by deep insertion of the intracochlear electrode, elaborate front end processing, anatomy based fitting (ABF), triphasic pulse stimulation instrumental in the suppression of facial nerve stimulation, and bimodal delay compensation allowing unilateral CI users to experience hearing with hearing aids on the contralateral ear. The large number of hardware developments might be exemplified by the RONDO, the world's first single unit audio processor in 2013. This article covers the milestones of translational research around the signal processing and audio processor topic that took place in association with MED-EL.

Low-Frequency Pitch Perception in Cochlear Implant Recipients With Normal Hearing in the Contralateral Ear

Purpose Three experiments were carried out to evaluate the low-frequency pitch perception of adults with unilateral hearing loss who received a cochlear implant (CI). Method Participants were recruited from a cohort of CI users with unilateral hearing loss and normal hearing in the contralateral ear. First, low-frequency pitch perception was assessed for the 5 most apical electrodes at 1, 3, 6, and 12 months after CI activation using an adaptive pitch-matching task. Participants listened with a coding strategy that presents low-frequency temporal fine structure (TFS) and compared the pitch to that of an acoustic target presented to the normal hearing ear. Next, participants listened with an envelope-only, continuous interleaved sampling strategy. Pitch perception was compared between coding strategies to assess the influence of TFS cues on low-frequency pitch perception. Finally, participants completed a vocal pitch-matching task to corroborate the results obtained with the adaptive pitch-matching task. Results Pitch matches roughly corresponded to electrode center frequencies (CFs) in the CI map. Adaptive pitch matches exceeded the CF for the most apical electrode, an effect that was larger for continuous interleaved sampling than TFS. Vocal pitch matches were variable but correlated with the CF of the 3 most apical electrodes. There was no evidence that pitch matches changed between the 1- and 12-month intervals. Conclusions Relatively accurate and asymptotic pitch perception was observed at the 1-month interval, indicating either very rapid acclimatization or the provision of familiar place and rate cues. Early availability of appropriate pitch cues could have played a role in the early improvements in localization and masked speech recognition previously observed in this cohort. Supplemental Material https://doi.org/10.23641/asha.8862389.

Contralateral Bimodal Stimulation: A Way to Enhance Speech Performance in Arabic-Speaking Cochlear Implant Patients

Background: The combination of acoustic and electric stimulation as a way to enhance speech recognition performance in cochlear implant (CI) users has generated considerable interest in the recent years. The purpose of this study was to evaluate the bimodal advantage of the FS4 speech processing strategy in combination with hearing aids (HA) as a means to improve low-frequency resolution in CI patients. Methods: Nineteen postlingual CI adults were selected to participate in this study. All patients wore implants on one side and HA on the contralateral side with residual hearing. Monosyllabic word recognition, speech in noise, and emotion and talker identification were assessed using CI with fine structure processing/FS4 and high-definition continuous interleaved sampling strategies, HA alone, and a combination of CI and HA. Results: The bimodal stimulation showed improvement in speech performance and emotion identification for the question/statement/order tasks, which was statistically significant compared to patients with CI alone, but there were no significant statistical differences in intragender talker discrimination and emotion identification for the happy/angry/neutral tasks. The poorest performance was obtained with HA only, and it was statistically significant compared to the other modalities. Conclusion: The bimodal stimulation showed enhanced speech performance in CI patients, and it improves the limitations provided by electric or acoustic stimulation alone.

Overlapping frequency coverage and simulated spatial cue effects on bimodal (electrical and acoustical) sentence recognition in noise

Sentence recognition in 20-talker babble was measured in eight Nucleus cochlear implant (CI) users with contralateral residual acoustic hearing. Speech reception thresholds (SRTs) were measured both in standard configurations, with some frequency regions presented both acoustically and electrically, and in configurations with no spectral overlap. In both cases a continuous interleaved sampling strategy was used. Mean SRTs were around 3 dB better with bimodal presentation than with CI alone in overlap configurations. A spherical head model was used to simulate azimuthal separation of speech and noise and provided no evidence of a contribution of spatial cues to bimodal benefit. There was no effect on bimodal performance of whether spectral overlap was present or was eliminated by switching off electrodes assigned to frequencies below the upper limit of acoustic hearing. In a subsequent experiment the CI was acutely re-mapped so that all available electrodes were used to cover frequencies not presented acoustically. This gave increased spectral resolution via the CI as assessed by formant frequency discrimination, but no improvement in bimodal performance compared to the configuration with overlap.

Detection of acoustic temporal fine structure by cochlear implant listeners: Behavioral results and computational modeling

A test of within-channel detection of acoustic temporal fine structure (aTFS) cues is presented. Eight cochlear implant listeners (CI) were asked to discriminate between two Schroeder-phase (SP) complexes using a two-alternative, forced-choice task. Because differences between the acoustic stimuli are primarily constrained to their aTFS, successful discrimination reflects a combination of the subjects' perception of and the strategy's ability to deliver aTFS cues.Subjects were mapped with single-channel Continuous Interleaved Sampling (CIS) and Simultaneous Analog Stimulation (SAS) strategies. To compare within- and across- channel delivery of aTFS cues, a 16-channel clinical HiRes strategy was also fitted. Throughout testing, SAS consistently outperformed the CIS strategy (p ≤ 0.002). For SP stimuli with F0 = 50 Hz, the highest discrimination scores were achieved with the HiRes encoding, followed by scores with the SAS and the CIS strategies, respectively. At 200 Hz, single-channel SAS performed better than HiRes (p = 0.022), demonstrating that under a more challenging testing condition, discrimination performance with a single-channel analog encoding can exceed that of a 16-channel pulsatile strategy.To better understand the intermediate steps of discrimination, a biophysical model was used to examine the neural discharges evoked by the SP stimuli. Discrimination estimates calculated from simulated neural responses successfully tracked the behavioral performance trends of single-channel CI listeners.

The potential of onset enhancement for increased speech intelligibility in auditory prostheses

Recent studies have shown that transient parts of a speech signal contribute most to speech intelligibility in normal-hearing listeners. In this study, the influence of enhancing the onsets of the envelope of the speech signal on speech intelligibility in noisy conditions using an eight channel cochlear implant vocoder simulation was investigated. The enhanced envelope (EE) strategy emphasizes the onsets of the speech envelope by deriving an additional peak signal at the onsets in each frequency band. A sentence recognition task in stationary speech shaped noise showed a significant speech reception threshold (SRT) improvement of 2.5 dB for the EE in comparison to the reference continuous interleaved sampling strategy and of 1.7 dB when an ideal Wiener filter was used for the onset extraction on the noisy signal. In a competitive talker condition, a significant SRT improvement of 2.6 dB was measured. A benefit was obtained in all experiments with the peak signal derived from the clean speech. Although the EE strategy is not effective in many real-life situations, the results suggest that there is potential for speech intelligibility improvement when an enhancement of the onsets of the speech envelope is included in the signal processing of auditory prostheses.

Correction to “A Normalized Beamforming Algorithm for Broadband Speech Using a Continuous Interleaved Sampling Strategy”

Correction to “A Normalized Beamforming Algorithm for Broadband Speech Using a Continuous Interleaved Sampling Strategy”

Effects of Pulse Width, Pulse Rate and Paired Electrode Stimulation on Psychophysical Measures of Dynamic Range and Speech Recognition in Cochlear Implants

In this article results are described of a study on the effects of stimulation rate (PR), pulse duration (PW), and paired pulsatile stimulation (PPS) versus continuous interleaved sampling (CIS) on speech perception and psychophysical loudness measures. During 3 nonconsecutive days, 27 postlingually deafened patients, implanted with either a CII or a HiRes90K with a HiFocus electrode array, were fitted with nine 12-channel strategies after a Latin-square design, systematically investigating the effect of stimulation rate (774-3868 pps/channel), PW (11-43 µsec/phase), and PPS versus CIS. Speech perception was measured in phonemes using open-set monosyllabic words. Minimum (T level) and maximum stimulation (M level) levels were measured. In general, performance was better with CIS strategies than with PPS strategies. There was little variation in speech perception performance between the different CIS strategies. As expected, PW and rate influenced the T and M levels in a systematic way for all electrode array positions. The T levels decreased by 2.11 dB per doubling of the pulse rate, whereas the M levels were considerably less influenced (slope -0.81 dB per doubling of the rate). T levels decreased 6.46 dB per doubling of pulse width, with an associated decrease in M levels of 5.58 dB, which is expressed in a closed-set formula. Changing from CIS to PPS led to a reduction of T levels by 1.34 dB and of M levels by 1.91 dB. This reduction was superimposed on the changes caused by doubling the rate, inherent to the PPS paradigm. CIS strategies tend to perform better than PPS strategies. PW, rate and paired stimulation have little effect on speech perception scores. However, they do have predictable and independent effects on both T and M levels for all strategies tested. The relationships found allow the improvement of the versatility of current fitting software and provide a basis to let the fitting software automatically adjust T and M levels if the PW or rate are adjusted in an existing program.

Recognition of Mandarin Chinese in noisy, reverberant environments

Cochlear-implant users partially recover their speech intelligibility in quiet but not in a noisy, reverberant environment, particularly for those speaking tonal languages, for which semantic information is also expressed by pitch contour. To improve cochlear-implant algorithms for tonal-language users, we have investigated speech recognition in Mandarin-Chinese speaking listeners under adverse listening condition to address four issues related to perceptual fusion and informational masking. First, to what extent do Chinese speech and non-speech sounds differ with respect to the tendency of perceptual fusion (between direct and reflected waves)? Second, why does perceptual separation provide a smaller release from informational masking in Mandarin Chinese than in English? Third, can the use of the recently developed simulated phase-locking stimulation strategy (SPLS, which extracts both phase and amplitude-envelope information) improve speech perception in Mandarin-speaking cochlear-implant patients compared to the continuous interleaved sampling strategy (CIS) currently in use? Fourth, does the prior presentation of a sentence spoken in quiet, by the same person who immediately afterwards produces a masked target sentence, improve identification of the masked target (voice priming) only for tonal-language speaking listeners?

A Normalized Beamforming Algorithm for Broadband Speech Using a Continuous Interleaved Sampling Strategy

The delay beamforming method, one of the most effective microphone array techniques, requires minimal computational complexity and enjoys wide usage in narrowband signal applications. However, the method suffers from high losses of low-frequency sound and is generally not suitable for broadband signals. In this paper, a novel normalized beamforming algorithm is introduced for broadband speech applications in multichannel cochlear implant (CI), which can be adjusted based on application conditions. The proposed algorithm can, with minimal computational complexity, accurately and effectively compensate for changes in signal beam pattern, in accordance with a preselected benchmark. In addition, this method can be combined with the widely used continuous interleaved sampling (CIS) strategy, adding to its practical value.

Adaptive Sample Reduction Techniques for Continuous Interleaved Sampling Strategy in Multi Channel Cochlear Implant

CIS (Continuous Interleaved Sampling) strategy in which electrodes stimulus is determined based on extracted information from amplitude of different bands of input signal, is a basis in processing methods in cochlear implant systems. In this paper besides implementing this strategy, methods for improving sample reduction and computational efficiency are also presented. In this case adaptive method according to processing parameters and an input signal has been suggested that due to the use of fewer samples to synthesize the signal is better than the other methods and is significantly efficient.

Comparison of Mandarin tone and speech perception between advanced combination encoder and continuous interleaved sampling speech-processing strategies in children

ObjectiveThis study was performed to compare cochlear implant (CI) users' performance in Mandarin speech and tone perception between 2 types of speech-processing strategies—advanced combination encoder (ACE) and continuous interleaved sampling (CIS)—under quiet and noisy conditions. MethodsThis study involved 10 congenitally deaf children (age range, 5.7–15.3 years; mean, 9.2 years) who received the Nucleus 24-channel CI system cochlear device (CI24R; Cochlear Ltd, Lane Cove NSW, Australia). The subjects used ACE since switching on their CI devices. Speech and tone perception tests were administered under quiet and noisy (+5 dB signal-to-noise ratio) conditions with ACE and CIS strategies 20 minutes and 2 weeks apart. ResultsRegardless of the strategy used, subjects showed significantly higher scores in speech perception than in tone recognition. Under noisy conditions, subjects had significantly higher tone identification scores with the CIS than the ACE strategy (P = .038). There was no significant difference in speech identification score between the strategies. Subjects showed significant higher tone identification and speech perception scores under quiet than noisy (+5 dB signal-to-noise ratio) conditions. Subjectively, 6 subjects preferred the ACE strategy, and the remaining 4 preferred the CIS strategy. The strategy preference of the subjects was related to speech perception performance rather than tone identification. A significant correlation was observed between tone identification and speech recognition, regardless of whether speech was evaluated by consonants (r = 0.669, P < .001), vowels (r = 0.426, P = .001), or sentences (r = 0.294, P = .023). ConclusionThere are only 4 patterns of tone in Mandarin, which is far fewer than the number of speech sounds. However, tone identification is poorer than speech perception. The CIS speech-processing strategy may improve tone identification under noisy conditions. Before improved speech strategies to code acoustic characteristics of tone can be developed, it would be worthwhile to try both CIS and ACE for CI users and to select the most suitable speech-processing strategy according to the subjective preference and objective performance.

From TEMPO+ to OPUS 2: What can music tests tell us about processor upgrades?

Tests for quantifying the music perception abilities of cochlear implant users are currently being developed and trialled at the South of England Cochlear Implant Centre. In addition to measures of speech perception, tests of rhythm, and pitch have been administered to MED-EL C40+ implant users before and after upgrading from the TEMPO+ processor with continuous interleaved sampling strategy to the OPUS 2 processor with fine structure processing strategy, with the aims of comparing device performance and evaluating the potential of music perception tests for informing processor upgrades and tuning. Eight experienced adult C40+ implant recipients performed tests of rhythm and pitch discrimination using the TEMPO+ processor and, after a minimum of 6 weeks acclimatization, using the OPUS 2 processor. Stimuli included piano and sine tones in two note ranges for the pitch tasks, and drum beats for the rhythm task. Rhythm, pitch, and speech perception scores were comparable for both processors. An effect of note range was observed (z = −2.52, p = 0.008 (two-tailed), r = −0.63), which indicated that the higher range of notes used for the pitch tasks was easier for participants than the lower range. Measures of pitch discrimination in different frequency ranges further informed changes made to one participant's map, resulting in improved pitch discrimination and speech perception scores. The outcomes of this study demonstrate that music perception tests can provide important additional measures for tuning cochlear implant parameters and assessing the impact of changes to device type and processing strategy.

Using spectral constancy to encode temporal pitch and improve cochlear-implant melody perception.

Despite good speech performance in quiet, melody perception remains a challenge to cochlear-implant (CI) users. Current CI pitch-encoding schemes significantly alter original signals, producing potentially detrimental effects on speech perception. The present study proposes to take advantage of spectral constancy to encode temporal pitch while minimizing signal distortion. Spectral constancy refers to unaltered timbre perception when the overall level of a signal is roved. For example, the vowel /a/ sounds the same independent of its overall level. The idea is to extract and encode pitch by increasing the gain of all channels proportionally and synchronously according to the pitch period. This scheme alters the temporal envelope of voiced sounds but preserves their spectral envelope in each time frame. It does not alter temporal envelope of unvoiced sounds, making it a good comprise between encoding pitch and preserving spectral and temporal envelopes. The new scheme has been implemented in a real-time speech processor and evaluated in nine nucleus CI users who identified ten melodies with minimal training and in a test protocol that randomized the stimulus presentation order. Compared with the standard continuous interleaved sampling strategy, the new scheme significantly improved CI melody perception by 10–20%.

Comparison of the fine structure processing (FSP) strategy and the CIS strategy used in the MED-EL cochlear implant system: Speech intelligibility and music sound quality

Objective: The aim of the present study was to evaluate MED-EL's Fine Structure Processing (FSP) strategy in comparison with their variations of the standard Continuous Interleaved Sampling (CIS) strategy denoted CIS+ and High Definition CIS (HDCIS). Study Sample: Twenty experienced adult CI users participated in the study in connection with upgrading to a new speech processor and at a two-year follow-up. Design: Blinded paired-comparisons between FSP and HDCIS were performed for speech intelligibility and music sound quality. Standard speech recognition tests in quiet and in noise were also accomplished to monitor the participants’ actual performance and to evaluate long-term outcomes. Results: Overall, the paired-comparison results showed no significant differences between the strategies, however, the total numbers of significant individual preferences were: 11 FSP vs. 12 HDCIS for speech, and 4 FSP vs. 15 HDCIS for music. The average speech recognition score decreased significantly after one month with FSP, but after two years there were no significant difference compared to the initial results with CIS+. Conclusions: Owing to the large individual differences in subjective preference, and the fact that the FSP strategy was not superior to the CIS variations, the recipients should be given the opportunity of choosing between the strategiesSumarioObjetivo: El objetivo de este estudio fue evaluar la estrategia de procesamiento de la estructura fina (FSP) de MED-EL en comparación con las variaciones de la estrategia estándar de muestreo intercalado continuo (CIS) denominado CIS+ y el CIS de alta definición (HDCIS). Muestra: Veinte adultos usuarios experimentados de CI participaron en este estudio en conexión con el ascenso a un nuevo procesador y el seguimiento durante dos años. Diseño: Se efectuó una comparación ciega pareada entre FSP y HDCIS para la inteligibilidad del lenguaje y la calidad del sonido musical. Se efectuaron también pruebas estándar de reconocimiento del lenguaje en silencio y en ruido para monitorear el desempeño de los participantes y para evaluar los resultados a largo plazo. Resultados: En general el resultado de la comparación pareada no mostró diferencias significativas entre las estrategias, sin embargo, los números totales de preferencias por sujeto fueron: 11 FSP vs 12 HDCIS para lenguaje y 4 FSP vs 15 HDCIS para la música. La puntuación promedio del reconocimiento del lenguaje disminuyó significativamente después de un mes con FSP, pero después de dos años no hubo diferencias significativas al comparar con los resultados iniciales del CIS+. Conclusiones: Debido a las amplias diferencias individuales en las preferencias de los sujetos y al hecho de que la estrategia FSP no fue superior a las variaciones de CIS, los receptores del CI deben tener la oportunidad de escoger entre las estrategias.

Sensitivity of Bimodal Listeners to Interaural Time Differences with Modulated Single- and Multiple-Channel Stimuli

In a previous study, it was shown that users of a cochlear implant and a contralateral hearing aid are sensitive to interaural time differences (ITDs). In the current study, we investigated (1) the influence on ITD sensitivity of bilaterally varying the place of excitation in the cochlea and of modulation frequency, and (2) the sensitivity to ITD with a 3-channel stimulus generated using continuous-interleaved-sampling (CIS)-like processing. The stimuli were (1) a high-frequency carrier (acoustic sinusoid and single-electrode electric pulse train), modulated with a half-wave-rectified low-frequency sinusoid (a so-called transposed stimulus), and (2) a 3-channel stimulus, generated by sending an acoustic click train through processing similar to the CIS strategy. Four bimodal listeners were sensitive to ITD for both stimulus types. For the first stimulus type, there was no significant influence on ITD sensitivity of the acoustic carrier frequency. Performance decreased with increasing modulation frequency with a limit of sensitivity at around 150–200 Hz. Sensitivity was similar for the single- and 3-channel stimulus. The results indicate the possibility of ITD perception with adapted clinical processors, which can lead to improved sound source localization and binaural unmasking.

Simulated Phase-Locking Stimulation: An Improved Speech Processing Strategy for Cochlear Implants

The continuous interleaved sampling (CIS) speech-processing strategy has been widely used for cochlear implants to extract speech envelope information without preserving phase information. In this study, a novel simulated phase-locking stimulation (SPLS) strategy, which detects zero-crossing times of the narrow-band signal of each band, was developed to extract both phase and amplitude-envelope information from a bank of frequency bands of speech sounds. The advantage of the SPLS strategy over the CIS strategy was confirmed by the results of our psychophysical experiments, showing that normal-hearing Chinese listeners’ performance in recognizing SPLS-processed Chinese speech was significantly better than their performance of recognizing CIS-processed Chinese speech under quiet, noise-masking, or speech-masking conditions. Thus, the results suggest that if the SPLS strategy is used to modulate the interval of electrical stimulation pulses in cochlear-implant devices according to extracted phase information, the speech-processing functions of cochlear implant devices would be improved for Chinese cochlear implant users.

A New Fine Structure Speech Coding Strategy

One of the most commonly used speech coding strategies for cochlear implants is continuous interleaved sampling (CIS), which codes the envelope information of an acoustic signal. Based on this strategy, MED-EL has recently developed the new fine structure processing (FSP) speech coding strategy, which also transmits subtle pitch and temporal cues. The aim of this study was to investigate the number of active channels necessary for good speech perception with FSP and whether there is an advantage for FSP compared with CIS at a reduced number of channels. Ten postlingually deafened patients using MED-EL Pulsar cochlear implants participated in this study. Patients were tested with all 12, 8, 5, 3, and 2 channels with CIS and FSP strategy, resulting in a total of 10 conditions. Performance was tested with numbers, monosyllables, and sentence tests. Our results showed an improvement in speech perception, with up to 5 channels for numbers and for monosyllables and sentence tests. Statistically significant increases in performance were noted from 3 to 8 channels for numbers, from 3 to 5 channels for monosyllables, and from 5 to 8 channels for sentence tests. No statistical significance was observed whether FSP or CIS was used. Based on these findings, the number of channels necessary for speech perception with FSP is similar to published results using CIS. There seems to be no advantage for FSP compared with CIS in the conditions of the present experiment.

Long‐Term Performance of Clarion 1.0 Cochlear Implant Users

To evaluate the long-term performance of adult Clarion 1.0 cochlear implant users. This was a retrospective, longitudinal study evaluating word discrimination in quiet for 31 adult cochlear implant patients with preimplantation sentence scores of less than 10%. The length of the study was 135 months with a mean follow-up length of 93 (median, 96) months. For the duration of the study, all subjects used the Clarion 1.0 cochlear implant with speech processors programmed for the use of the continuous interleaved sampling strategy. There was no significant growth or decline in speech perception after 24 months postimplantation unless adverse medical events were experienced. Age at implantation was significantly and substantially negatively correlated (-11% word score per decade, r = 0.68) with most recent score, maximum score, time to maximum score, range of performance, 24- to 130-month mean score, and for any longitudinal data point tested: 3 to 6 months, 6 months, 1 year, 2 years, 5 years, and 10 years. There were no age-related declines in performance. There were no observed correlations between duration of deafness and any of the variables listed above. The lack of correlation between duration of deafness and performance in a cohort without residual hearing suggests the presence of a strong correlation between age and speech performance with a cochlear implant. That the cochlear implant is a safe therapy for the treatment of profound deafness is supported by the stability of scores through the 10-year study period as well as a zero rate of device failures or explantation.