Speech perception results in children implanted with Clarion devices: Hi-Resolution and Standard Resolution modes

Development of auditory and language skills in children using cochlear implants with two signal processing strategies

Introduction

The increase in the spectral information offered by the sound processing strategy HiRes 120 has led to great expectations for the pediatric population. Due to a shorter duration of auditory deprivation and higher neural plasticity, children could benefit more substantially from the spectral information of this sound processing strategy.

Objective

To compare auditory and language skills in Brazilian children with cochlear implants using the HiRes and HiRes 120 sound processing strategies.

Methods

Thirty children, aged 1–3 years, with congenital hearing loss, were divided into two groups, according to the signal processing strategy adjusted at the time of the cochlear implant activation. The assessed children were matched according to chronological age and the time of the cochlear implant use. The auditory and language skills were evaluated longitudinally through the Infant-Toddler Meaningful Auditory Integration Scale and Production Infant Scale Evaluation, carried out before surgery, and 3, 6 and 12 months after device implantation. The Mann–Whitney test was applied for the comparison between the two groups with a 5% significance level.

Results

The findings indicated development of hearing and language skills in the first year of cochlear implant use; however, there was no statistically significant difference in the evolution of such skills due to the adjusted processing strategy in the activation of the cochlear implant electrodes.

Conclusion

The development of auditory and language skills in the assessed children was similar during the entire study period, regardless of which signal processing strategy was used.

Effects of Converting Bilateral Cochlear Implant Subjects to a Strategy with Increased Rate and Number of Channels

Objectives:

Three different Advanced Bionics processing strategies were evaluated: 1) 8-channel, 813 pulses per second (pps), Continuous Interleaved Sampling (CIS); 2) 16-channel, 5,100 pps, HiResolution Paired (HiRes P); and 3) 16-channel, 2,900 pps, HiResolution Sequential (HiRes S).

Methods:

Seven adult bilateral Clarion CII cochlear implant recipients who had been using a CIS processing strategy for at least 18 months participated in this study. Sentence recognition in multitalker babble from the front was collected on subjects using their CIS strategy and after subjects were programmed for the first time with HiRes P and HiRes S strategies. An ABAB design was implemented for 1 month whereby subjects used each HiResolution strategy every other day. Sentence recognition testing was repeated at the 1- and 3-month post-HiResolution test intervals.

Results:

Comparisons between the CIS and HiResolution strategies showed immediate improvements for 5 subjects in favor of the HiResolution strategies. After 1 month of alternating between the HiRes P and HiRes S strategies, remarkably, 2 subjects showed improvements of 60%, 2 subjects showed improvements of 40%, and 2 subjects showed improvements of 30% over the CIS strategy that they had previously used for at least 18 months. The results after 3 months of use were consistent with those obtained at 1 month.

Conclusions:

The HiRes S and HiRes P strategies resulted in dramatic improvements in speech perception in noise for a subset of subjects who had been using the CIS strategy bilaterally. This finding demonstrates that these subjects were able to tolerate a more difficult signal-to-noise ratio. Further work is needed to determine the independent effects of rate versus number of channels.

Influence of signal processing strategy in auditory abilities

The signal processing strategy is a parameter that may influence the auditory performance of cochlear implant and is important to optimize this parameter to provide better speech perception, especially in difficult listening situations.

OBJECTIVE

To evaluate the individual's auditory performance using two different signal processing strategy.

METHOD

Prospective study with 11 prelingually deafened children with open-set speech recognition. A within-subjects design was used to compare performance with standard HiRes and HiRes 120 in three different moments. During test sessions, subject's performance was evaluated by warble-tone sound-field thresholds, speech perception evaluation, in quiet and in noise.

RESULTS

In the silence, children S1, S4, S5, S7 showed better performance with the HiRes 120 strategy and children S2, S9, S11 showed better performance with the HiRes strategy. In the noise was also observed that some children performed better using the HiRes 120 strategy and other with HiRes.

CONCLUSION

Not all children presented the same pattern of response to the different strategies used in this study, which reinforces the need to look at optimizing cochlear implant clinical programming.

Contralateral implantation in children affected by postimplant meningitis

This study was designed to investigate the indication and advantages of contralateral implantation after postimplant meningitis (piM). Speech perception assessment, most comfortable levels and high-resolution computer tomography were used to monitor cochlear fibrosis/ossification and clinical changes in outcomes in 5 children affected by meningitis after a variable-time post-cochlear implantation. Ipsilateral ossification was found in 3 children, 1 of whom developed delayed contralateral ossification. These children were implanted on the contralateral side as they all showed deterioration of hearing performance. Results from the present paper and literature analysis suggest that, (1) piM can induce ipsilateral and contralateral ossification, (2) meningitis-induced cochlear ossification is more prone to develop in the presence of a normal cochlear structure and (3) contralateral implantation after piM has proven to be effective in restoring performance when a full electrode insertion is accomplished.

Implementation of perceptual channels in children implanted with a HiRes 90K device

CONCLUSIONS

The increased spectral resolution that characterizes the HiRes 120 device contributes to improvement of performance. Discrimination and identification in noise are consistent with reports of improved perception under everyday listening situations.

OBJECTIVES

This work focuses on speech perception findings after implementation of current steering in HiResolution strategy of children implanted with Clarion HiRes 90K.

SUBJECTS AND METHODS

Comparison was made between three groups of children: standard HiRes control group, a second group switched over from HiRes to HiRes 120 and the third group switched on with HiRes 120. Children were tested before and 12 months after implementation of HiRes 120. A standard test battery was administered to obtain a speech perception development profile. The Auditory Speech Sound Evaluation (A section signE) test was carried out to evaluate discrimination and identification of phonemes in quiet and in noise.

RESULTS

The HiRes and HiRes 120 switch-over groups showed quite similar results for speech perception in quiet. However, the HiRes 120 switch-over group achieved these results within a shorter time after conversion. Switch-on children showed improvement in all speech perception categories, reaching approximately 60% recognition and 30% comprehension in quiet. Results for A section signE discrimination scores in quiet and noise showed a clear improvement for both HiRes 120 switch-on and switch-over groups compared with the HiRes group.

Comparison between the IT-MAIS and MUSS questionnaires with video-recording for evaluation of children who may receive a cochlear implantation

There is a great difficulty in determining earlier on which children would benefit or not from cochlear implants, especially because of their young age, the responses they give are very subtle.

AIM

To compare results obtained through video-recording of the interactions of children who may receive a cochlear implant with the results obtained through evaluation protocols.

METHOD

Seven children, with an average age of 39.7 months, with profound hearing loss were selected for the study. IT-MAIS and MUSS questionnaires were given to their parents/guardians of these children and the results were compared with the observation of the video-recordings.

RESULTS

It was possible to observe that the data is compatible with the auditory stages. However, the MUSS questionnaire data gathered during playful activities is very different . The questionnaire only takes into consideration the use of verbal language and therefore the majority of the evaluated children inevitably score low.

CONCLUSION

Observing children play allows us to trace a better profile of linguistic behavior and aspects relative to language, that may presented differences in the questionnaire.

Comparação entre os questionários IT-MAIS e MUSS com vídeo-gravação para avaliação de crianças candidatas ao implante coclear

Existe uma grande dificuldade para determinar precocemente crianças que se beneficiariam ou não com o implante coclear, até porque devido à pouca idade são muito sutis as respostas apresentadas. OBJETIVO: Comparar os resultados obtidos através da vídeo-gravação de situações de interação de crianças candidatas ao implante coclear com os resultados obtidos através de protocolos de avaliação. MÉTODO: Fizeram parte da amostra 7 crianças com idade média de 39,7 meses, portadores de perda auditiva neurossensorial profunda. Foram aplicados os questionários IT-MAIS e MUSS aos pais e os resultados foram comparados com a observação da vídeo-gravação destas crianças. RESULTADOS: Foi possível observar que os dados são compatíveis no que se refere às etapas auditivas. No entanto, no que se refere ao questionário MUSS, os dados obtidos na observação lúdica são bastante diferentes. O questionário leva em consideração apenas a uso da linguagem oral e, portanto, a maioria das crianças apresentou um escore muito baixo. CONCLUSÃO: A observação lúdica permitiu traçar um perfil mais amplo do comportamento lingüístico e de aspectos relativos à linguagem apresentando diferenças do questionário.

Focused intracochlear electric stimulation with phased array channels

A method is described for producing focused intracochlear electric stimulation using an array of N electrodes. For each electrode site, N weights are computed that define the ratios of positive and negative electrode currents required to produce cancellation of the voltage within scala tympani at all of the N-1 other sites. Multiple sites can be stimulated simultaneously by superposition of their respective current vectors. The method allows N independent stimulus waveforms to be delivered to each of the N electrode sites without spatial overlap. Channel interaction from current spread associated with monopolar stimulation is substantially eliminated. The method operates by inverting the spread functions of individual monopoles as measured with the other electrodes. The method was implemented and validated with data from three human subjects implanted with 22-electrode perimodiolar arrays. Results indicate that (1) focusing is realizable with realistic precision; (2) focusing comes at the cost of increased total stimulation current; (3) uncanceled voltages that arise beyond the ends of the array are weak except when stimulating the two end channels; and (4) close perimodiolar positioning of the electrodes may be important for minimizing stimulation current and sensitivity to measurement errors.

Effects of interaural time differences in fine structure and envelope on lateral discrimination in electric hearing

Bilateral cochlear implant (CI) listeners currently use stimulation strategies which encode interaural time differences (ITD) in the temporal envelope but which do not transmit ITD in the fine structure, due to the constant phase in the electric pulse train. To determine the utility of encoding ITD in the fine structure, ITD-based lateralization was investigated with four CI listeners and four normal hearing (NH) subjects listening to a simulation of electric stimulation. Lateralization discrimination was tested at different pulse rates for various combinations of independently controlled fine structure ITD and envelope ITD. Results for electric hearing show that the fine structure ITD had the strongest impact on lateralization at lower pulse rates, with significant effects for pulse rates up to 800 pulses per second. At higher pulse rates, lateralization discrimination depended solely on the envelope ITD. The data suggest that bilateral CI listeners benefit from transmitting fine structure ITD at lower pulse rates. However, there were strong interindividual differences: the better performing CI listeners performed comparably to the NH listeners.