Cochlear Implants in Five Cases of Auditory Neuropathy: Postoperative Findings and Progress

Objectives To review our experiences with some of the preoperative and postoperative findings in five children who were diagnosed with auditory neuropathy and were provided with cochlear implants. We describe changes in auditory function, which enabled these children to have significant improvement in their hearing and communication skills. Study Design Pre‐ and postoperatively, these children received complete medical examinations at Mayo Clinic, including related consultations in audiology, pediatrics, neurology, medical genetics, otolaryngology, psychology, speech pathology, and radiology. Methods These children typically had additional medical and audiological examinations at more than one medical center. The hearing assessments of these children included appropriate behavioral audiometric techniques, objective measures of middle ear function, acoustic reflex studies, transient (TOAE) or distortion product (DPOAE) otoacoustic emissions, auditory brainstem responses (ABR), and, in some cases, transtympanic electrocochleography (ECoG). After placement of the internal cochlear implant devices (Nucleus CI24), intraoperatively we measured electrode impedances, visually detected electrical stapedius reflexes (VESR) and neural response telemetry (NRT). These intraoperative objective measures were used to help program the speech processor for each child. Postoperatively, each child has had regular follow‐up to assure complete healing of the surgical incision, to assess their general medical conditions, and for speech processor programming. Their hearing and communication skills have been assessed on a regular basis. Postoperatively, we have also repeated electrode impedance measurements, NRT measurements, otoacoustic emissions, and electrical auditory brainstem responses (EABR). We now have 1 year or more follow‐up information on the five children. Results The five children implanted at Mayo Clinic Rochester have not had any postoperative medical or cochlear implant device complications. All of the children have shown significant improvements in their sound detection, speech perception abilities and communication skills. All of the children have shown evidence of good NRT results. All but case D (who was not tested) showed evidence of good postoperative EABR results. Otoacoustic emissions typically remained in the non‐operated ear but, as expected, they are now absent in the operated ear. Conclusion Our experiences with cochlear implantation for children diagnosed with auditory neuropathy have been very positive. The five children we have implanted have not had any complications postoperatively, and each child has shown improved listening and communication skills that have enabled each child to take advantage of different communication and educational options.     

Implantation of the ossified cochlea: management with the split electrode array

OBJECTIVES/HYPOTHESIS: To describe indications for, the surgical technique required, and the expected functional results of split electrode array cochlear implants. STUDY DESIGN: Retrospective chart review. METHODS: Data collected included etiology of deafness, radiographic findings, pre- and postoperative aided pure tone thresholds, and speech perception testing. Adult speech perception outcomes were measured using the Consonant Nucleus Consonant (CNC) monosyllable words and Hearing in Noise Test (HINT) in quiet/noise (+10 dB). The children were assessed using the Infants and Toddlers Meaningful Auditory Integration Scale. RESULTS: Five patients were implanted with a split electrode array. This included two adults and three children. Both adults had preoperative binaural aided pure tone averages worse than 50 dB and scores of 0% on both HINT quiet and CNC words. The children had undetectable preoperative aided thresholds and scored an average 4/40 on the IT-MAIS. Postimplant, the average threshold gain was 38.5 dB in the adults and 81.5 dB in the children. One adult improved to score 51%/22% on HINT quiet/noise at 6 months and 72%/30% at 12 months. The other adult continued to score 0% on HINT at 12 months but claimed substantial subjective auditory improvement after the first year of device use. The children averaged 28/40 on the IT MAIS at 6 months after implantation. Forty-two of 48 implanted electrodes were functional. CONCLUSIONS: The split electrode array is a useful alternative to traditional cochlear implants in treating deafened patients with cochlear ossification. Patients implanted with the split array show marked improvement in sound and speech perception.     

The role of age in pediatric cochlear implantation

OBJECTIVE: To document progress, benefit and importance of age in paediatric cochlear implantation. DESIGN: The EARS (Evaluation of Auditory Responses to Speech) test battery was performed on 33 prelingually deaf children at regular intervals up to 36 months following implantation. All children participated in individually tailored intensive audiological rehabilitation programs after receiving their implants. In this respect, it was attempted to evaluate speech perception scores in children implanted before and after the age of 3 in a homogenous group. RESULTS: All children demonstrated encouraging improvements over time in their speech recognition abilities. Furthermore, it was observed that the children who were implanted under the age of 3 achieved higher levels of speech perception performance. CONCLUSION: In order to shorten the process of central maturation of the auditory system, it is desirable to implant the children as young as possible. Early intervention seems to be the ideal strategy in enabling prelingually deaf children to derive maximum benefit from cochlear implantation.     

Cochlear implantation in children with congenital inner ear malformations

OBJECTIVE/HYPOTHESIS: To assess the audiologic and surgical outcomes for pediatric cochlear implant patients with inner ear malformations. STUDY DESIGN: Retrospective review of 315 pediatric cochlear implant cases from 1994 to 2002. METHODS: Twenty-eight pediatric cochlear implant patients with known inner ear malformations determined on high-resolution computed tomography (HRCT) of the temporal bone were the subjects of review. Results of HRCT findings, intraoperative findings, postoperative complications, and objective measures of both closed- and open-set testing of speech perception were analyzed. RESULTS: Patients with the constellation of an incompletely partitioned (IP) cochlea, enlarged vestibular aqueduct (EVA), and a dilated vestibule (i.e., Mondini's malformation) as well as those with an isolated EVA or partial semicircular canal aplasia have relatively good levels of speech perception. Patients with total semicircular canal aplasia, isolated IP, cochlear hypoplasia, or common cavity demonstrated lower levels of performance. Poor performance may be related to associated developmental delays rather than labyrinthine anatomy alone. Complications of surgery were relatively limited. CONCLUSIONS: Cochlear implantation can be successfully performed in children with inner ear malformations. These children and their parents can expect significant auditory benefits from this intervention. The various types of inner ear malformations may have quite different prognoses for good auditory performance.     

Impact of auditory cortical asymmetry in cochlear implantation

Abstract

Objective

Is there a cochlear implant ear advantage for speech perception?

Patients

A total number of 68 cochlear implant recipients were evaluated retrospectively. They were 20 adults implanted in right ear, 20 matched adults implanted in left ear while 14 children implanted in right ear and 14 matched children implanted in left ear.

Methods

Behavioral responses & age based speech perception tests were evaluated at 6 months and 1 year post implantation.

Results

Adult showed no statistical difference in all tests at 6 months evaluation while 1 year evaluation showed significant better performance for right implanted group in monosyllabic discrimination test. Children showed statistical significant performance in monosyllabic identification and minimal pairs testes at 6 months evaluation; and in monosyllabic identification only at 1 year evaluation.

Conclusion

The present data support that right ear implantation would fasten the development of auditory skills especially in young children, an issue to be considered in unilateral implantation.     

Implication of central asymmetry in speech processing on selecting the ear for cochlear implantation.

OBJECTIVE: Emerging evidence in auditory neuroscience suggests that central auditory pathways process speech asymmetrically. In concert with left cortical specialization for speech, a "right-ear advantage" in speech perception has been identified. The purpose of this study is to determine if this central asymmetry in speech processing has implications for selecting the ear for cochlear implantation. STUDY DESIGN: Retrospective cohort study. SETTING: Academic university medical center PATIENTS: One hundred one adults with bilateral severe-to-profound sensorineural hearing loss INTERVENTION: Cochlear implantation with the Nucleus 24 Contour device. MAIN OUTCOME MEASUREMENTS: Patients were divided into two groups according to the ear implanted. Results were compared between left-ear- and right-ear-implanted patients. Further subgroup analysis was undertaken, limited to right-handed patients. Postoperative improvement on audiograms and scores on speech perception tests (Hearing in Noise test, City University of New York in quiet and in noise test, Consonant-Vowel Nucleus- Consonant words, and phonemes) at 1 year was compared between groups. Analysis of covariance was used to control for any intergroup differences in preoperative characteristics. RESULTS: The groups were matched in age, duration of hearing loss, duration of hearing aid use, percentage implanted in the better hearing ear, and preoperative audiologic testing. Postoperatively, there were no differences between left-ear- and right-ear-implanted patients in improvement on speech recognition tests. CONCLUSION: Despite central asymmetry in speech processing, our data do not support a right-ear advantage in speech perception outcomes with cochlear implantation. Therefore, among the many factors in choosing the ear for cochlear implantation, central asymmetry in speech processing does not seem to be a contributor to postoperative speech recognition outcomes.     

Audiological performance after cochlear implantation: a 2-year follow-up in children with inner ear malformations

CONCLUSIONS: Open-set speech perception in children with an inner ear malformation is equal to that of other congenitally deaf children after an average of 2 years follow-up. OBJECTIVE: To analyze audiological performance after cochlear implantation in a sample of children with radiographically detectable malformations of the inner ear compared to performance in prelingually deafened children at large. MATERIALS AND METHODS: Nine children with osseous inner ear malformations were compared to 22 congenitally deaf children, all of whom underwent cochlear implantation. All subjects were tested on their electrical evoked compound action potential. Speech perception tests were performed using the monosyllabic trochee polysyllabic test without visual support and the open-set monosyllabic wordlist. RESULTS: In all, 20% of the congenitally deaf children in our center study have inner ear abnormalities. Inner ear malformations were limited to incomplete partition of the cochlea; none of the subjects had common cavity malformations. Electrical compound action potentials were successfully recorded in both groups intraoperatively. Speech perception tests on open-set speech yielded an average of 48.8% (SD 21.2%) in the group of children with inner ear malformations vs 54.5% (SD 21.1%) in congenitally deaf children. In four of nine cases with an inner ear malformation we encountered a minor CSF leak.     

Predicting speech perception outcomes following cochlear implantation in adults with unilateral deafness or highly asymmetric hearing loss

Objective: Unilateral deafness and highly asymmetric hearing loss can impair listening abilities in everyday situations, create substantial audiological handicap, and reduce overall quality of life. Preliminary evidence suggests that cochlear implantation may be effective in reversing some of these detrimental effects. Patient-level data from existing studies were re-analysed to explore potential factors that may be predictive of improved speech perception scores following implantation.

Methods: Logistic regression modelling examined whether improved speech perception following implantation under various listening conditions was related to the duration of deafness of the severe-to-profoundly deaf ear and/or the level of hearing in the better ear.

Results: Patients with a shorter duration of deafness were more likely to improve in listening conditions that created a less favourable SNR at the implanted ear than the non-implanted ear. Those with more residual hearing in the better ear were more likely to improve in the listening condition that created a less favourable SNR at that ear.

Discussion: The analysis suggests that characteristics of both ears may be relevant when seeking to identify those candidates who are likely to obtain benefit to speech perception following cochlear implantation.     

Is there a right cochlear implant advantage?

OBJECTIVE: To compare behavioral speech perception performance of children with right versus left cochlear implants (CIs). STUDY DESIGN: A retrospective cohort study. SETTING: Academic university medical center. SUBJECTS: Seventy-one prelingually deafened children that obtained a CI device at 48 months or younger. INTERVENTION: Cochlear implantation with Cochlear, Advanced Bionics, and Med-El devices. MAIN OUTCOME MEASUREMENTS: Patients were divided into 2 groups according to ear of implant (right, n = 30; left, n = 41) and matched in age at implantation and preoperative audiologic results. Multivariate analysis of variance was used to evaluate the effects of 1) side of CI, 2) age at implantation, 3) time with CI (T1, 18-24 mo; T2, 36-42 mo), and 4) dominance (i.e., compatibility between CI side and handedness) on performance in a monosyllabic open-set test scored for words and phonemes. RESULTS: A small yet significant "right CI advantage" was evident throughout the study follow-up and was independent of age at implantation. The performance of children implanted at 24 months or younger was significantly higher than that of children implanted between 25 and 48 months. Regardless of CI side and age at implantation, all children exhibited improvement in speech perception with continuous use. CONCLUSION: The present study provides first-time evidence for a right CI advantage for speech perception in prelingually deafened children that can be taken into account when selecting side of CI in candidates with similar residual hearing in both ears and no anatomic constraints. The present data lend further support to the notions that greater gains in speech perception are associated with earlier age at implantation and continuous use.     

Cochlear implantation in children with inner ear malformations

OBJECTIVES: The aim of this study was to assess the outcomes of cochlear implantation in children with inner ear malformations (IEMs). METHODS: A retrospective review of 212 children who received implants from September 1994 to May 2004 was performed. Forty-six of them had radiologic evidence of IEMs. The preoperative evaluations, intraoperative findings, postoperative complications, and performance outcomes were analyzed. For the comparative analysis of performance outcomes, the children with IEMs were matched and compared with children with a normal inner ear who had received implants. Statistical analysis was performed with a repeated-measures analysis of variance. RESULTS: All of the children were studied with computed tomography and magnetic resonance imaging. Three-dimensional volume rendering of magnetic resonance images was performed in cases that were difficult to interpret because of structural complexity. The operative findings included aberrant facial nerves in 2 children and cerebrospinal fluid gushers in 22 children. Intraoperative fluoroscopic examination was performed to evaluate electrode placement. There were no serious postoperative complications. All children with IEMs achieved open-set speech perception abilities, except for the children with a narrow internal auditory canal (IAC), and showed progressive improvement of their speech perception abilities over time. There were no statistically significant differences in performance measured by the Common Phrases test between the 2 groups. Although the repeated-measures analysis of variance indicated that children with IEMs performed more poorly than those with a normal inner ear on the Phonetically Balanced Kindergarten test for phonemes, statistical significance was not found at 2 years after implantation. The children with a narrow IAC benefited from the implantation and used the device every day, although their speech perception abilities were limited. CONCLUSIONS: The results of the present study show that cochlear implantation can be performed relatively safely in deaf children with IEMs and that they receive considerable benefit from their implants. Substantial benefit can be expected from implantation in children with most kinds of IEMs, except for a narrow IAC, which is often associated with limited results.     

Audiological performance after cochlear implantation: a 2-year follow-up in children with inner ear malformations

Conclusions: Open-set speech perception in children with an inner ear malformation is equal to that of other congenitally deaf children after an average of 2 years follow-up. Objective: To analyze audiological performance after cochlear implantation in a sample of children with radiographically detectable malformations of the inner ear compared to performance in prelingually deafened children at large. Materials and methods: Nine children with osseous inner ear malformations were compared to 22 congenitally deaf children, all of whom underwent cochlear implantation. All subjects were tested on their electrical evoked compound action potential. Speech perception tests were performed using the monosyllabic trochee polysyllabic test without visual support and the open-set monosyllabic wordlist. Results: In all, 20% of the congenitally deaf children in our center study have inner ear abnormalities. Inner ear malformations were limited to incomplete partition of the cochlea; none of the subjects had common cavity malformations. Electrical compound action potentials were successfully recorded in both groups intraoperatively. Speech perception tests on open-set speech yielded an average of 48.8% (SD 21.2%) in the group of children with inner ear malformations vs 54.5% (SD 21.1%) in congenitally deaf children. In four of nine cases with an inner ear malformation we encountered a minor CSF leak.     

有低频残余听力感音神经聋的人工耳蜗植入术

目的介绍一种有低频残余听力感音神经聋的人工耳蜗植入技术,探讨人工耳蜗植入手术对有残余听力患者的治疗效果和价值。方法15例有残余听力的患者接受了保护残余听力的人工耳蜗植入手术。术中电极植入深度在19mm～24mm左右。术后分别检测单纯使用助听器、单纯使用人工耳蜗、人工耳蜗结合助听器三种不同状态下的听力。结果15例患者中,有13例术后残余听力保存良好,仅分别丢失5～20dB听力,但另2例术后残余听力全部丧失。术后在安静、信噪比15dB和10dB三种不同状态下的言语测试结果显示,人工耳蜗结合助听器使用者测试得分始终保持在很高水平;单纯使用人工耳蜗者也有较好的成绩,但在信噪比达10dB的条件下,测试成绩下降;而单纯使用助听器者,不仅在安静状态下听力成绩不甚理想,一旦加入竞争性噪声,听力测试成绩急剧下降。结论保护和利用残余听力的人工耳蜗植入技术,使人工耳蜗植入手术对象从重度或极重度聋扩大到高频为重度或极重度聋,低频（≤500Hz）为中、轻度聋的患者。接受这项技术患者的听力和言语识别能力均明显优于其单纯配戴助听器和单纯使用人工耳蜗时的听力和言语识别能力。     

Role of neck ultrasound during follow-up care of head and neck squamous cell carcinomas

Cantonese language rehabilitation in 28 prelingually deaf children who underwent cochlear implantation was evaluated. All patients were implanted with multichannel devices and the operations went smoothly. They all had improved scores on audiological assessments and speech perception tests. The speech evaluation tests included the recognition of sounds, vowels, consonants and tone. Sentence recognition and story comprehension were both improved after training for 2 years. Cochlear implantation is a useful measure for the speech rehabilitation of prelingually profound deaf children when hearing aids are of no benefit. The multichannel implant device is of clinical significance in the rehabilitation of those patients using tonal language.     

Chinese tonal language rehabilitation following cochlear implantation in children

Cantonese language rehabilitation in 28 prelingually deaf children who underwent cochlear implantation was evaluated. All patients were implanted with multichannel devices and the operations went smoothly. They all had improved scores on audiological assessments and speech perception tests. The speech evaluation tests included the recognition of sounds, vowels, consonants and tone. Sentence recognition and story comprehension were both improved after training for 2 years. Cochlear implantation is a useful measure for the speech rehabilitation of prelingually profound deaf children when hearing aids are of no benefit. The multichannel implant device is of clinical significance in the rehabilitation of those patients using tonal language.     

Effect of age at cochlear implantation on open-set word recognition in Mandarin speaking deaf children

OBJECTIVE: The purpose of this study was to determine whether age at cochlear implantation influences open-set speech perception in children after long-term use of the implant device. METHOD: Twenty-eight congenitally deafened children, receiving implants of Nucleus CI24M devices, were divided into two groups: (1) CI < 3: those who received implants before 3 years of age and (2) CI > 3: those who received implants after 3 years of age. We compared open-set speech perception in CI < 3 and CI > 3 after 4-5 years of device use. Speech perception tests were conducted using the Mandarin Lexical Neighborhood Test (M-LNT). Unpaired t-test was applied for statistical analysis, and p < 0.05 was considered significant. RESULTS: In CI < 3, the average of percent correct was 80.0 +/- 8.8 and 70.5 +/- 9.2% on, respectively, the easy and hard versions of the M-LNT. By contrast, in CI > 3, the average percent correct was 62.5 +/- 19.9 and 59.1 +/- 15.2%, respectively. Regardless of the M-LNT version used, CI < 3 performed significantly better than CI > 3 (easy, p = 0.005 versus hard, p = 0.022). CONCLUSION: The present investigation demonstrated that age at implantation influences open-set speech perception of cochlear implanted children 4-5 years after device connection. Implantation before 3 years of age promotes the development of open-set speech perception abilities in congenitally deafened children.     

The prognostic value of promontory electric auditory brain stem response in pediatric cochlear implantation

OBJECTIVE: To test the hypothesis that children with clear promontory electrically evoked auditory brain stem responses (prom-EABRs) would outperform, after cochlear implantation, children who had no prom-EABR preoperatively. DesigN: A prospective study was undertaken on 47 implanted children assigning them to two groups (group A: 35 children with a clear wave e-V in the preoperative prom-EABR and group B: 12 children with no prom-EABR). Speech perception and speech intelligibility were assessed annually up to 3 yr after implantation with the IOWA sentence test (level A and level B), Connected Discourse Tracking, Categories of Auditory Performance, and Speech Intelligibility Rating. t-test and Mann-Whitney U test were used to compare the above outcome measures in the two groups. RESULTS: There was no statistically significant difference between the two groups on any of the outcome measures at any interval. Moreover, the small differences observed showed no consistent trend toward either group of children. Further analysis revealed that the outcomes have not been affected by possible confounding factors (age at implantation, duration of deafness, preoperative unaided pure-tone thresholds, and number of inserted electrodes). CONCLUSIONS: The results suggest that children with no prom-EABR performed at levels comparable with children who had clear promontory responses preoperatively. The prognostic value of prom-EABR is limited and absence of a prom-EABR is not, by itself, a contraindication for cochlear implantation. However, in selected cases (congenital malformations, cochlear nerve dysplasia or suspected aplasia, narrow internal auditory canal, etc.) the presence of a prom-EABR is a positive finding in the assessment of candidates for cochlear implantation as it confirms the existence of intact auditory neurones.     

Cochlear implantation in children with inner ear malformations: report of two cases

Cochlear implantation of congenitally deaf children with inner ear malformations is gaining special interest. Although the number of the reported cases is increasing, the decision for implantation needs thorough investigation. Preoperative evaluation, surgical approach and postoperative follow-up can be challenging. STUDY DESIGN: A retrospective analysis of two cases with inner ear malformations. PATIENTS: One patient was a 3-year-old-girl who had cochlear and cochleovestibular nerve aplasia on the left side and incomplete partition on the other side. The other patient was a 5-year-old-boy who had hypoplastic cochlea on both sides. Both of them also had vestibular anomalies. Cases were implanted by using multichannel cochlear implant. RESULTS: No complications were encountered. Both patients responded to acoustic stimuli, and their speech perception skills were improved. After 10 months of cochlear implant use, their results seem encouraging. CONCLUSION: Except cochlear or cochleovestibular nerve agenesis, inner ear malformations cannot be accepted as a contraindication for cochlear implantation. Although there can be difficulties during the surgery or in the postoperative period, patients with inner ear malformations can also benefit from cochlear implantation. It is essential that all possible complications and postoperative performance should be discussed with the parents.     

综合听力学评价对小龄聋儿人工耳蜗术前适应证筛选的临床意义

目的探讨综合听力学评价对判断小龄聋儿人工耳蜗植入适应证的临床意义。方法对50名3岁以内小龄聋儿进行听觉脑干诱发电位（auditory brainstem responses,ABR）、耳声发射（otoacoustic emissions,OAE）、声导抗等客观测试。行为观察（behavioral observation audiometry。BOA）、视觉强化定向反应（visual reinforcement audiometry,VRA）、游戏测听（play audiometry,PA）等行为测听及听觉言语评估,用其结果综合判断听力损失程度。术后开机3个月对所有小儿进行听觉言语评估,与术前结果进行对比。结果术后50名聋儿的听觉言语识别率有明显提高。结论综合听力学评价能够准确筛选出小龄聋儿人工耳蜗适应证患者,筛选出来的患者术后可以取得较好的康复效果。     

Three‐year follow‐up of children with postmeningitic deafness and partial cochlear implant insertion

Objectives: To evaluate the long‐term outcome of children with postmeningitic deafness and partial insertion of the Nucleus electrode array, and to compare their speech perception performance with that of children with full insertion of the electrode array. Design: A battery of seven speech perception tests was administered to 25 children with a cochlear implant (CI). Results were reduced into one score: equivalent hearing loss (EHL). Setting: Tertiary referral centre. Participants: The partial insertion group comprised seven children, mean age at implantation 5.5 years, mean duration of deafness 3.6 years. The full‐insertion control group comprised 18 children. Mean age at implantation: 4.4 years; mean duration of deafness: 2.9 years. All the children became deaf between 0 and 3 years of age. Main outcome measures: Over a 3‐year follow‐up period, the children with partial insertion showed continuing progress, although there was wide variation in performance and the rate of progression. Some open‐set comprehension could even be achieved with the insertion of only eight electrodes of a nucleus device. Results: Three years after implantation, speech perception in the partial insertion children was poorer than that in the control groups with long (P < 0.01; 95% confidence interval 7–43 dB EHL) and short duration of deafness (P < 0.0001; 95% confidence interval 28–53 dB EHL). They showed slower progress and reached a poorer EHL plateau. Four of the seven children acquired open‐set word recognition. Conclusions: Patients with partial insertion of the electrode array benefit from a CI, although less than patients with complete insertion.     

Short electrode insertion in cochlear implantation: speech perception performance of Cantonese-speaking subjects

CONCLUSIONS: Subjects with cochlear ossification derived benefits in terms of speech performance similar to those of the non-ossified group. It is thus recommended that the insertion of short electrode arrays should be considered an alternative choice for patients with cochlear ossification. OBJECTIVE: Cochlear ossification has been recognized as a major obstacle to the full insertion of a multichannel cochlear implant electrode array. To alleviate the technical difficulty of placing a standard electrode array and the possibility of causing undesirable trauma to the cochlea, a newly designed electrode array with the same number of electrodes compressed into a shorter length has been made available. The aim of the present study was to examine the speech perception performance of patients implanted with the MED-EL C40+S compressed electrode array and to compare their results with those of matched groups implanted with the MED-EL C40+standard electrode array. MATERIAL AND METHODS: One pre-lingually and two post-lingually deaf subjects using short electrode arrays were matched with three groups of subjects using standard electrode arrays. The pre- and postoperative speech perception scores were evaluated. RESULTS: All three subjects using compressed electrode arrays achieved speech perception scores comparable to those of matched subjects using standard electrode arrays. There was also a tendency for the subjects to show similar patterns of speech perception scores as a function of the difficulty of the tests.