Comparison of continuous interleaved sampling and simultaneous analog stimulation speech processing strategies in newly implanted adults with a Clarion 1.2 cochlear implant.

OBJECTIVE: This study consisted of a within-subjects comparison of speech recognition and patient preference when subjects used two different cochlear implant speech processing strategies with a Clarion 1.2 (enhanced bipolar) device: Simultaneous Analog Stimulation (SAS), and Continuous Interleaved Sampling (CIS). These two strategies used two different electrode configurations: the SAS strategy used bipolar stimulation, whereas the CIS strategy used monopolar stimulation. STUDY DESIGN: This was a multicenter study that used a within-subjects balanced crossover design. Experience with the two strategies was replicated in each subject using an ABAB design. Order of strategy use was balanced across all subjects. SETTING: The study was carried out at several cochlear implant centers affiliated with tertiary medical centers. PATIENTS: Subjects consisted of 25 postlingually deafened adults who received a Clarion cochlear implant. INTERVENTIONS: Total involvement by each subject was 14 weeks. Speech perception testing and sound quality assessments were performed after use with each strategy. MAIN OUTCOME MEASURES: Primary outcome measures include speech perception data and patient responses to questionnaires regarding speech and sound quality. RESULTS: Analyses revealed that performance did not differ significantly by the strategy encountered first as relative to the strategy encountered second and that the order in which a strategy was used did not appear to affect subjects' eventual preference for a particular strategy. Although speech recognition scores tended to be higher for CIS for most of the test measures at most of the test intervals, the analysis of variance to evaluate differences in strategy did not reveal a significant effect of strategy. Further analysis of scores obtained at the replication interval, however, revealed that scores obtained with CIS were significantly higher than scores obtained with SAS on the Hearing in Noise Test sentences in quiet and noise. In addition, significantly more patients indicated a final preference for the CIS strategy than for the SAS strategy. Importantly, both the analysis evaluating order and the analysis evaluating strategy revealed significant effects of evaluation period, indicating that time/experience with the implant had a significant effect on scores for each strategy, regardless of the order in which it was used (first or second). CONCLUSIONS: This study demonstrates that important learning occurs during the first several weeks of cochlear implant use, making it difficult to adequately compare performance with different speech processing strategies. However, the finding that patients often prefer the strategy they understand speech the best with supports the clinical practice of letting adult patients select their preferred strategy without formally evaluating speech perception with each available strategy.     

A high rate n-of-m speech processing strategy for the first generation Clarion cochlear implant

Abstract

An n-of-m speech coding strategy has been developed for the Clarion Cochlear Implant Series 1.x (1.0 & 1.2). The basic principle is to reduce the number of stimuli per cycle, by neglecting the less significant spectral components, and to concentrate on the more dominant frequency bands. In this study 20 subjects, implanted with a Clarion device, used an n-of-m strategy at 1666 pps per channel. The outcomes using this strategy were compared with the outcomes using conventional processing (CIS at 833 pps/channel). Eight of the 20 subjects underwent additional testing with the n-of-m strategy with the rate set at 833 pps/channel. Using the n-of-m strategy at 1666 pps showed statistically significant improvement in performance over the CIS strategy, with 16 of the 20 subjects achieving better results. However, there was no statistically meaningful difference in performance between n-of-m at 833 pps and the CIS strategy running at the same rate. Results therefore suggest that n-of-m strategy can be an alternative to CIS, particularly when the implant hardware limits the overall stimulation rate.

Sumario

Se ha desarrollado una estrategia n-of-m de codificación del lenguaje para el implante coclear Clarion en sus series 1 × (1.0 & 1.2). El principio básico es reducir el número de estímulos por ciclo, abandonando los componentes espectrales menos significativos y concentrándose en las bandas de frecuencia más dominantes. En este estudio 20 sujetos implantados con un Clarion, usaron una estrategia n-of-m a 1666 pps por canal. Los resultados con el uso de esta estrategia se compararon con los obtenidos al usar procesamiento convencional (CIS a 833 pps/ canal).Ocho de los 20 sujetos realizaron pruebas adicionales con la estrategia n-of-m a una tasa de 833 pps/canal. El uso de la estrategia n-of-m a 1666 pps mostró una mejoría estadísticamente significativa en el rendimiento, en comparación con la estrategia CIS, en 16 de los 20 sujetos que obtuvieron mejores resultados. No obstante, no hubo una diferencia estadísticamente significativa en el rendimiento entre la condición de 833 pps y la estrategia CIS, practicadas a la misma tasa. Los resultados sugieren por consiguiente que la estrategia n-of-m puede ser una alternativa de la CIS, particularmente cuando el equipo limita la tasa total de estimulación.     

Comparison of two cochlear implant coding strategies on speech perception

Objective: Assess whether differences in speech perception are observed after exclusive listening experience with high-definition continuous interleaved sampling (HDCIS) versus fine structure processing (FSP) coding strategies.

Methods: Subjects were randomly assigned at initial activation of the external speech processor to receive the HDCIS or FSP coding strategy. Frequency filter assignments were consistent across subjects. The speech perception test battery included CNC words in quiet, HINT sentences in quiet and steady noise (+10?dB SNR), AzBio sentences in quiet and a 10-talker babble (+10?dB SNR), and BKB-SIN. Assessment intervals included 1, 3, and 6 months post-activation.

Results: Data from 22 subjects (11 with HDCIS and 11 with FSP) were assessed over time. Speech perception performance was not significantly different between groups.

Discussion: Speech perception performance was not significantly different after 6 months of listening experience with the HDCIS or FSP coding strategy.     

Comparison of the TEMPO+ ear-level speech processor and the cis pro+ body-worn processor in adult MED-EL cochlear implant users

A study was conducted to compare the new MED-EL TEMPO+ ear-level speech processor with the CIS PRO+ body-worn processor in the COMBI 40/COMBI 40+ implant system. Speech tests were performed in 46 experienced subjects in two test sessions approximately 4 weeks apart. Subjects were switched over from the CIS PRO+ to the TEMPO+ in the first session and used only the TEMPO+ in the time between the two sessions. Speech tests included monosyllabic word tests and sentence tests via the telephone. An adaptive noise method was used to adjust each subject's scores to approximately 50%. Additionally, subjects had to complete a questionnaire based on their 4 weeks of experience with the TEMPO+. The speech test results showed a statistically significant improvement in the monosyllabic word scores with the TEMPO+. In addition, in the second session, subjects showed a significant improvement when using the telephone with the TEMPO+, indicating some learning in this task. In the questionnaire, the vast majority of subjects found that the TEMPO+ allows equal or better speech understanding and rated the sound quality of the TEMPO+ higher. All these objective and subjective results indicate the superiority of the TEMPO+ and are mainly attributed to a new coding strategy called CIS+ and its implementation in the TEMPO+. In other words, based on the results of this study, it appears that after switching over from the CIS PRO+ to the TEMPO+, subjects are able to maintain or even improve their own speech understanding capability.     

Evaluation of the high-resolution speech coding strategy for the Clarion CII cochlear implant system

Four postlinguistically deafened adults were implanted with the Clarion CII cochlear implant with the HiFocus II electrode in an evaluation of performance with a new speech coding strategy (high resolution) compared with current speech coding strategies (multiple pulsatile sampler, continuous interleaved sampling, and simultaneous analog stimulation). These strategies were implemented in the Platinum speech processor from Advanced Bionics Corporation (Sylmar, CA). Postoperatively, subjects were fitted with the traditional coding strategies and over the first month were allowed to determine their strategy of choice. This strategy was used to evaluate open-set speech recognition performance at 1 month and 3 months postfitting. At 3 months postfitting, subjects were reprogrammed with the high-resolution strategy. They returned for speech recognition testing at 1 month and 3 months postfitting with this strategy. Performance was significantly better with the high-resolution strategy for all four subjects, particularly when listening to speech in background noise. This finding was in agreement with their strong preference for the high-resolution strategy, and all four patients continue to use the high-resolution strategy.     

A comparison of cochlear implant processing strategies in children using speech pattern audiometry

The aim of this study was to use Speech Pattern Audiometry (SPA) to compare phoneme perception performance between SPEAK and ACE processing strategies with children using the Nucleus 24 cochlear implant. Listeners were evaluated in terms of ability to identify two synthetic word pairs, one signalling a voicing contrast and the other signalling a place of articulation contrast. For both word pairs, ACE was associated with more 'normal' phoneme boundaries than SPEAK. There was also a non-significant trend for better identification ability with ACE compared to SPEAK. The study suggests that there may be a place for SPA as part of the clinical battery of tests used for evaluation of cochlear implant speech processing strategies in children. Copyright (c) 2005 John Wiley & Sons, Ltd.     

人工耳蜗的言语编码方案与汉语声母语谱特点

人工耳蜗植入方面的研究迄今已有50余年的历史，为聋人尤其是聋儿重建听力和发展言语能力起到了重要的作用。随着最近20余年在人工耳蜗言语信号处理方面的飞速发展，使植入者的言语识别能力有了明显提高．很多报道显示大部分使用了新的言语编码方案的患者对于单词．短句、甚至是复杂句子的识别正确率都有了很大提高。     

Initial information on adjustment of speech processor of the cochlear implant

Adjustment of a speech processor of the cochlear implant is the first procedure in rehabilitation of patients after cochlear implantation. Influence of setting understated and overstated threshold levels of current perception on processing of a speech signal was studied. The results of the study show that only precise estimation of current perception threshold and comfortable loudness allow transmitting maximal acoustic information for each patient.     

Initial evaluation of the Clarion CII cochlear implant: speech perception and neural response imaging

OBJECTIVE: To evaluate the new Clarion CII cochlear implant with the perimodiolar HiFocus electrode array, including both speech perception outcomes and the device's capabilities of measuring the electrically evoked compound action potential (eCAP) of the auditory nerve (Neural Response Imaging, NRI). DESIGN: The speech perception scores on CVC words without lip reading were monitored prospectively for the 10 postlingually deaf patients implanted with the Clarion CII device in the period July 2000 until May 2001 in the Leiden University Medical Center. Preoperative and postoperative NRI recordings were made, applying various combinations of monopolar stimulating and recording electrodes with the alternating polarity paradigm available in the test bench software. RESULTS: Nine patients preferred the CIS, one the PPS strategy, none the SAS strategy. With their favorite strategy they acquired significant open set speech understanding within a few weeks, resulting in an average CVC phoneme score of 84% (word score 66%) at the end of the study (follow-up 3 to 11 mo). In speech-shaped noise, the average phoneme recognition threshold (PRT) was reached at a signal to noise ratio just below 0 dB. The NRI recordings had clear N1 and P1 peaks if there was at least one contact between the stimulating and recording electrodes, necessitating just 15 sweeps for a reliable recording. We observed considerable inter-patient and inter-electrode variability, but for a given situation NRI input/output curves were stable over time. More apical contacts generally elicited larger eCAPs. Response amplitudes tended to peak at recording sites around apical and basal stimulating electrodes, suggesting a limited spread of excitation. Preliminary recordings with the forward masking paradigm were consistent with the ones with the alternating polarity scheme. CONCLUSIONS: The Clarion CII is a promising cochlear implant with which our first 10 patients have obtained excellent speech perception results. The NRI system yields high quality signals with a limited number of sweeps at a high sampling rate.     

Comparison of speech recognition ability with different speech processing strategies by Korean cochlear implantees.

Many variables affect the audiologic performance of cochlear implantees. With current methods of evaluation, it is difficult to directly compare auditory function with different speech coding strategies. We compared the audiologic performance directly with F0F1F2 and multipeak speech coding strategies in the same implanted ear of eight Korean cochlear implantees. We tested word and phoneme recognition abilities using Korean word lists for speech audiometry and two-syllable nonsense words, respectively. With the multipeak coding strategy, a significant difference in discrimination ability was found in the initial fricative consonant phonemes (/s/,/ss/,/h/). Our results suggest that the improvement of speech recognition ability with the multipeak coding strategy comes primarily from the better understanding of the initial fricative consonants.     

Handling of the TEMPO+ behind-the-ear speech processor by MED-EL cochlear implant users

Abstract

MED-EL launched its ear-level speech processor, the TEMPO+, in 1999. Studies have already demonstrated improved speech perception, sound quality and the ability to enjoy music with the TEMPO+ due to the new CIS+ speech-coding strategy. This study evaluated responses to 185 questionnaires about ease of handling and usage of the TEMPO+, opinion of and satisfaction with the TEMPO+ and its performance, as well as satisfaction with accessories. There was particular interest in seeing if the TEMPO+ was suitable for use with children. Results showed that MED-EL cochlear implant users felt comfortable manipulating the dials and switches, changing the battery pack, using external sources of input and with provided accessories. Overall, there was satisfaction with the TEMPO+. Notably, one third of respondents were under the age of 10. Results show the suitability of the TEMPO+ behind-the-ear speech processor for young children.     

Cochlear implant speech processor frequency allocations may influence pitch perception.

OBJECTIVE: To investigate the effects of assigning cochlear implant speech processor frequencies normally associated with more apical cochlear locations to the shallow insertion depths of the Iowa/Nucleus Hybrid electrode. STUDY DESIGN: Subjects using the Hybrid implant for more than 1 year were tested on speech recognition with Consonant-Nucleus-Consonant words and consonant stimuli. Pitch sensations of individual electrodes were also measured electrically through the implant and acoustically in the contralateral ear. SETTING: Tertiary care center. RESULTS: Most subjects showed large improvements in speech recognition within 12 months after implantation. Furthermore, after longer periods of 24-plus months, some individuals were able to achieve high levels of consonant discrimination with electric-only processing comparable to long-electrode patients with deeper electrode insertions. Pitch perceptions obtained from individual electrodes in these subjects were closer to the frequency map assigned an electrode than the place-frequency predicted from cochlear location. CONCLUSION: These results suggest that over time, pitch sensations may be determined more by the implant map than by cochlear location. In other words, the brain may adapt to spectral mismatches by remapping pitch. Furthermore, patients can perform well with shifted frequency allocations for speech recognition. The successful application of shifted frequency allocations also supports the idea of shallower insertions and greater preservation of residual hearing for all cochlear implants, regardless of the patient's frequency range of usable residual hearing.     

Handling of the TEMPO+ behind-the-ear speech processor by MED-EL cochlear implant users

MED-EL launched its ear-level speech processor, the TEMPO+, in 1999. Studies have already demonstrated improved speech perception, sound quality and the ability to enjoy music with the TEMPO+ due to the new CIS+ speech-coding strategy. This study evaluated responses to 185 questionnaires about ease of handling and usage of the TEMPO+, opinion of and satisfaction with the TEMPO+ and its performance, as well as satisfaction with accessories. There was particular interest in seeing if the TEMPO+ was suitable for use with children. Results showed that MED-EL cochlear implant users felt comfortable manipulating the dials and switches, changing the battery pack, using external sources of input and with provided accessories. Overall, there was satisfaction with the TEMPO+. Notably, one third of respondents were under the age of 10. Results show the suitability of the TEMPO+ behind-the-ear speech processor for young children.     

A comparison of two training strategies for speech recognition with an electrotactile speech processor

Seven normally hearing adults were trained in the use of a multiple-channel electrotactile speech processor for 70 hours over a 6-month period. Two training strategies were used on each of the subjects: (1) analytic-plus-synthetic (AS), and (2) synthetic (S). The speech perception abilities of the subjects were assessed with closed sets of vowels and consonants, open sets of words and sentences, and speech tracking, for the tactile-plus-lipreading, tactile, and lipreading conditions. The subjects were tested on three separate occasions: (1) at the beginning of the study, (2) after 35 hours of training, and (3) after a further 35 hours of training. Wilcoxon matched-pair signed-ranks (MPSR) tests showed that improvements observed with both the AS and S strategies were significantly (p less than .05) greater than zero for most tests and conditions. The Wilcoxon MPSR test showed that the difference in improvements between the training strategies was significant for only the vowel and consonant tests in the tactile condition.     

Emotional and analytic music perception in cochlear implant users after optimizing the speech processor

The present study examined transmitters that regulate commissural inhibition. Extracellular spikes of a single vestibular neuron were recorded in decerebrated cats. Multibarreled electrodes were filled with transmitter candidates (GABA and glycine), their specific antagonists (bicuculline, strychnine) and 2 M NaCl for extracellular recording. After isolation of a type I neuron, chemicals were iontophoretically applied to examine their effects on the activity of the neuron. The results were as follows. Commissural inhibition caused by electrical stimulation of the contralateral labyrinth was not abolished by the application of strychnine (a glycine antagonist), but was abolished by bicuculline (a GABA antagonist). Commissural inhibition was not abolished by phaclofen. Some bicuculline-sensitive neurons, with a short-latency commissural inhibition (presumably disynaptic inhibition), showed spacial summation when the conditioning stimulation (contralateral vestibular nerve stimulation) was applied with the test stimulation (vestibular nucleus stimulation). It was concluded that commissural inhibition was activated by the GABA_A receptor, but not by the GABA_B receptor, that the inhibitory type I neurons located in the contralateral vestibular nucleus were GABAergic, and that inhibitory type II neurons were also GABAergic neurons.     

Long-term performance of Clarion 1.0 cochlear implant users

OBJECTIVE/HYPOTHESIS: To evaluate the long-term performance of adult Clarion 1.0 cochlear implant users. STUDY DESIGN: 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%. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.     

Averaged electrode voltages in users of the Clarion cochlear implant device

Averaged electrode voltages (AEVs) are of secondary importance for integrity testing of cochlear implant devices featuring back-telemetry. However, AEVs are device-independent and may show intermittent failures and deviant stimulation patterns unnoticed by telemetry. We collected AEVs from 18 users of the Clarion 1.2 system and 6 users of the HiFocus system in order to establish norms for evaluating AEVs in difficult cases. The stimuli were presented with the standard clinical software. Monopolar stimulation at about 16 microA showed large AEVs (mean, 173 microV) suitable for integrity testing. No electrode failures were found. The AEV amplitudes from neighboring electrodes differed by less than 30% (2 SD). The AEVs from subjects with the Clarion HiFocus electrode and/or the Clarion electrode positioner were within the normal range. The AEV amplitudes from bipolar stimulation were much more variable. Inversion of phases between electrodes was found in patients with an altered state of the cochlea (otosclerosis and osteogenesis imperfecta) and in a patient with a curled electrode tip. There was no correlation across subjects between AEVs and electrode impedances. Therefore, impedances are dominated by the electrode-tissue interface, in contrast to AEVs, which are determined by the volume conduction in the body.