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PubMed1985

A comparison of three speech coding strategies using an acoustic model of a cochlear implant.

Three alternative speech coding strategies suitable for use with cochlear implants were compared in a study of three normally hearing subjects using an acoustic model of a multiple-channel cochlear implant. The first strategy (F2) presented the amplitude envelope of the speech and the second formant frequency. The second strategy (F0 F2) included the voice fundamental frequency, and the third strategy (F0 F1 F2) presented the first formant frequency as well. Discourse level testing with the speech tracking method showed a clear superiority of the F0 F1 F2 strategy when the auditory information was used to supplement lipreading. Tracking rates averaged over three subjects for nine 10-min sessions were 40 wpm for F2, 52 wpm for F0 F2, and 66 wpm for F0 F1 F2. Vowel and consonant confusion studies and a test of prosodic information were carried out with auditory information only. The vowel test showed a significant difference between the strategies, but no differences were found for the other tests. It was concluded that the amplitude and duration cues common to all three strategies accounted for the levels of consonant and prosodic information received by the subjects, while the different tracking rates were a consequence of the better vowel recognition and the more natural quality of the F0 F1 F2 strategy.

Adult↗

PubMed2004

Criteria of candidacy for unilateral cochlear implantation in postlingually deafened adults III: prospective evaluation of an actuarial approach to defining a criterion.

OBJECTIVE: Outcomes from unilateral cochlear implantation in postlingually deafened adults are variable and difficult to predict precisely from data gathered before surgery. The objective was to derive and validate a method for specifying criteria of candidacy for implantation that takes this variability into account. DESIGN: Accuracy of identifying words in prerecorded sentences without lipreading was measured in 480 users of unilateral multichannel cochlear implants. These patients had all scored zero before surgery on prerecorded open-set tests of word recognition in sentences with acoustic hearing aids. Statistical models were derived that calculated the odds that a patient would score higher with an implant than a criterion score, given knowledge of the duration of profound deafness in the implanted ear. The accuracy of the models was evaluated prospectively with two new groups of patients who scored between 1% and approximately 50% correct before surgery in one or both ears with acoustic hearing aids. Group I (N=53) was implanted in an ear that scored zero. Group II (N=31) was implanted in an ear that scored above zero. Benefits from implantation, measured as changes in word recognition performance and in health utility, were compared with the odds calculated by the statistical models. RESULTS: The preferred model was based on data from 376 subjects. It made accurate predictions of the proportion of patients in group I, and, disregarding minor exceptions, accurate predictions of the proportion of patients in group II, who improved on their preoperative word recognition score. Benefit from implantation was low for patients implanted with odds less favorable than 4:1 (4 chances out of 5). CONCLUSIONS: Adoption of odds of 4:1 as the criterion of candidacy for unilateral cochlear implantation would be likely to maintain acceptable benefit and cost-effectiveness while being explicit and informative for patients, clinicians, and commissioners of health care.

Actuarial Analysis↗

PubMed2002

[Electrically evoked auditory nerve compound action potentials in Nucleus CI24M cochlear implant users].

OBJECTIVE: To study the feasibility and clinical applicability of electrically evoked auditory nerve compound action potentials (ECAP) in young patients with Nucleus CI24M cochlear implants. METHOD: ECAPs have been recorded from 37 Nucleus CI24M cochlear implant users in response to monopolar electrical stimulation of the cochlea by using the neural response telemetry(NRT) software and the hardware. Behavioral thresholds and maximum comfortable levels were measured in 12 of those patients. RESULT: ECAPs could be recorded in 87.6% of all patients. Good relations were observed between ECAP threshold and behavioral threshold, but poor relations between ECAP threshold and the impedance of different electrodes. We also observed growth functions and threshold variations of ECAP across subjects for a given place as well as across electrodes within a subject. These findings might be that these particular physiological measures are related to the number of living neural fibers and the excitability of the auditory nerve to electrical stimulation. CONCLUSION: ECAPs were proved to be useful in adjusting the stimulation parameters of the cochlear implant speech processor in order to maximize an individual's performance with the device, especially in young children.

Action Potentials↗

PubMed2006

Partial deafness cochlear implantation provides benefit to a new population of individuals with hearing loss.

CONCLUSION: Partial deafness cochlear implantation (PDCI) is a feasible means of treating individuals who have good low frequency hearing, but a severe to profound hearing loss in the mid to high frequencies. The individuals have benefit in noise and show significant benefit in a number of difficult listening conditions, when compared with their acoustic-only hearing prior to implantation. This benefit is maintained over time. OBJECTIVES: PDCI using the round window surgical technique is one means of treating individuals with a 'ski-slope' hearing loss, who gain minimal benefit from amplification with conventional hearing instruments. This paper aims to demonstrate the benefit that PDCI provides these individuals. PATIENTS AND METHODS: Ten subjects received a partial insertion of a standard MED-EL electrode, using the round window approach. Pure tone audiometry and monosyllable testing in quiet and noise were conducted preoperatively, at implant fitting and then at 1, 3, 6 and 12 months after initial device fitting. The APHAB questionnaire was completed by subjects preoperatively and then at 6 and 12 months after receiving their cochlear implant. RESULTS: Hearing was preserved in 9 of 10 cases. One subject uses a hearing aid to amplify low frequency hearing, the remainder use natural low frequency hearing. Improvements in monosyllabic scores over time in both quiet and noise were significant, particularly within the first 3 months of PDCI use.

Adult↗

PubMed1996

Audiological findings after multichannel cochlear implantation in patients with Mondini dysplasia.

Mondini dysplasia is a congenital malformation of the inner ear. To date, five individuals with this malformation have received cochlear implants at the South of England Cochlear Implant Centre. The aim of this study was to review the audiological findings of these individuals after implantation. The soundfield thresholds after implantation are in the region of 30-40 dB (A). The results of suprathreshold speech recognition tasks show substantial variability in performance but this is no greater than that obtained from implant users with no malformation. All individuals were able to detect and recognize a variety of environmental sounds that would previously have been inaudible. These findings, along with the reported improvement in quality of life, mean that Mondini dysplasia is not a contra-indication for multichannel cochlear implantation. This information will be useful to other centres when considering implantation in similar patients.

Audiometry↗

PubMed2001

[Cochlear implantation: relationship between speech development and insertion depth in children].

BACKGROUND: The goal in pediatric cochlear implantation is improved hearing leading to better speech development, which may allow their integration into mainstream schools. Whether the intracochlear position of the electrode array has an influence on speech development or not is controversially discussed. PATIENTS: Between 1996 and 1998 29 children ranging from 1.5 to 11.8 years (median 4 years) were provided with a Nucleus 22M or 24M cochlear implant system. Speech and language skills were assessed by a closed-set test (Mainzer test) and by the Schmid-Giovannini score for hearing development pre-implantation and at 6, 12, 18 and 24 months post-implantation. The position of the electrode array was determined by the surgical record and by a postoperative transorbital x-ray. Since the promontory has a thickness of one to two electrode bands, we defined deep insertion as more than 24 bands intracochlear. RESULTS: The patients were divided into 2 groups according to the insertion depth: Group 1 (n = 8) 24 bands (22 electrodes and 2 stiffening rings correspond to < or = 18 mm) or less and group 2 (n = 21) more than 24 bands intracochlear correspond to > 18 mm). The mean closed-set test scores 12 months post-implantation were 51.4% and 68.5% for group 1 and group 2, respectively. Schmid-Giovannini test scores were 8.7 for group 1 and 10.1 for group 2. There was no significant statistical difference in the closed-set and Schmid-Giovannini test scores. We observed incomplete insertion (i.e. less than 22 active bands are intracochlear) because of electrode extrusion in only one child. CONCLUSION: Speech development in children does not improve with deeper insertion of the cochlear implant electrode array.

Age Factors↗

PubMed2002

Electrophysiological findings in two bilateral cochlear implant cases: does the duration of deafness affect electrically evoked auditory brain stem responses?

Bilateral cochlear implantation provides an interesting model for in vivo study of the effect of long-term profound deafness on neural transmission. We present electrophysiological observations on 2 patients implanted with the MXM Binaural Digisonic Convex system. This uncommon design consists of 2 electrode arrays placed bilaterally into the scala tympani and controlled by a single speech processor. In both patients, the duration of deafness before cochlear implantation clearly differed from one ear to the other. Electrically evoked auditory brain stem responses (EABRs) were measured and the EABRs from the ear with the longer deafness duration showed a lengthening of wave V latency. In I patient, recordings from this ear also showed a lack of reproducibility of wave III. The data suggest that neural responsiveness in the peripheral and intermediate auditory pathways is adversely affected by deafness duration. Poor EABRs on one ear possibly result from the total duration of deafness in this ear and/or compensation by the other ear.

Adult↗

PubMed1991

Educational management of children with cochlear implants.

During the last decade, the technology of assistive hearing devices for hearing-impaired children has improved significantly. Improvements in hearing aids and the introduction of cochlear implants and wearable tactile aids for children have made spoken language available to more deaf children and have changed the techniques for teaching listening and speaking skills. In June 1990, the Food and Drug Administration approved the Nucleus 22 channel cochlear implant for use with children. As a result, it is expected that more children will be implanted and, consequently, that the teachers and audiologist in the schools in which they are enrolled will need to learn to manage the devices. Since the Nucleus 22 cochlear implant does not restore normal hearing, children will continue to need instruction in listening and speaking. Furthermore, school personnel, who will be responsible for caring for and monitoring the implants, will have to learn how to maintain the devices. This article outlines some procedures for maximizing the benefits that profoundly deaf children can achieve with the cochlear implant.

Child↗

PubMed1992

Phoneme recognition by deaf individuals using the multichannel nucleus cochlear implant.

Experiments have been carried out to determine which cues are used in phoneme identification by deaf individuals using a cochlear implant. Five deaf individuals with a Nucleus 22-channel cochlear implant were tested with open set speech audiometry in free field without lipreading. Speech material consisted of lists of Dutch words of the Consonant-Vowel-Consonant type (CVC-words). Word scores ranged from 0 to 22%, phoneme scores from 11 to 54%. For each subject the responses to the initial consonant, the vowel and the final consonant were entered into separate confusion matrices. Kruskal analysis, which provided a geometric representation of these confusions, showed that in the recognition of consonants the feature of voicing is all important. Vowels were identified on the basis of the frequencies of the first and second formants. In one subject the electrode array could only partially be inserted into the cochlea, leaving roughly half the second formant area of the electrode array outside the cochlea. For this subject vowel identification was based upon the first formant and vowel duration; there was no contribution of second formant information to vowel identification. Compressing the first and second formant frequency to the limited intracochlear array did not enhance transmission of second formant information and did not improve performance. The basic findings for consonant and vowel recognition could be explained by the speech coding strategy of the Nucleus speech processor in which voicing determines stimulus periodicity and formant frequencies determine channel selection. Kruskal analysis of phoneme confusions may aid in programming and evaluating the performance of the Nucleus cochlear implant.

Adult↗

PubMed1995

A clinical report on receptive vocabulary skills in cochlear implant users.

OBJECTIVES: The aim was to measure the rate of vocabulary acquisition for cochlear implant users and compare the pre- and postoperative rates with published data for other groups with normal or impaired hearing. The hypothesis was that the postoperative rate would be greater than the preoperative rate. DESIGN: The Peabody Picture Vocabulary Test (PPVT) was administered to 32 children, adolescents, and prelinguistically deafened adults implanted with the 22-electrode cochlear implant. Age at implantation ranged from 2 yr 6 mo to 20 yr and implant use ranged from 6 mo to 7 yr 8 mo. RESULTS: The group mean postoperative performance at various postoperative intervals was significantly higher than mean preoperative performance. Single-subject data indicated statistically significant gains over time on this test for 13 of the subjects. The mean postoperative rate of vocabulary acquisition of 1.06 times the rate for normally hearing children was significantly greater than the mean preoperative rate of 0.43. CONCLUSION: These rates of improvement were in accord with previous reports on smaller numbers of implant users, but could not be attributed unambiguously to use of the implant because no control group was used for this clinical work. Variables such as age at implantation, duration of profound deafness, communication mode, and speech perception skill failed to significantly predict rate of improvement of the PPVT.

Adolescent↗

PubMed2002

Receptive and expressive language skills of children with five years of experience using a cochlear implant.

The language of 7 children who had used a cochlear implant for 5 years was evaluated by means of the Clinical Evaluation of Language Fundamentals-3, the Peabody Picture Vocabulary Test-Revised, and the Expressive Vocabulary Subtest of the Test of Word Knowledge. All subjects demonstrated impaired skills relative to normal-hearing children on 1 or more subtests. Variability in performance occurred between subjects and within subjects across subtests. Strengths in semantic skills were evident compared to weaker syntactic and morphological abilities. The nature of the subjects' language impairments is considered with reference to language delay and specific language impairment. The findings support the need for further evaluation of the rate and course of development of language subskills. Investigation of the influences of information processing, and learning styles and strategies, on children's outcomes is also warranted. These findings have implications for implementation of optimal habilitation and education programs for children with cochlear implants.

Child↗

PubMed2006

[Subjetive benefits and limitations in relation with the cochlear implant reported by adolescent and adult patients].

OBJECTIVE: To identify the subjetive benefits and limitations of the pre and postlingually adolescent and adult patients of the cochlear implants program at Clinical Hospital San Cecilio (Granada). MATERIAL AND METHODS: Cross-sectional study of 60 pre and postlingually deaf patients who received cochlear implant with more than 12 years and at least a year of experience. A open-ended questionnaire was used to value their subjetive experience. A descriptive analysis was made and we applied the square Chi and Mann-Withney tests. RESULTS: The average implant usage per day was greater in the postlingually patients (14.6 hours) that in the prelingually (10.4 hours). Between the acoustic benefits, both more frequent were the perception of environmental sounds and the possibility of to converse easier, specially with one or two persons. The benefit more indicated by the patients was the improvement in its mood. The perception in noise situations was the difficulty more indicated by all patients. The problems, in relation with the device, more frequently indicated were the size and the weight. CONCLUSION: the cochlear implant provides subjetive benefits to the patients that complement their improvement in perception of the oral language and facilitate the re/integration of the deaf patients at his work and in his social life. Therefore, the speech perception tests must be complemented with another type of materials to value the result of the cochlear implant and then we will can to speak of success or failure.

Adolescent↗

PubMed1994

Maintaining the Ineraid cochlear implant.

Managing a patient with acquired profound deafness with a cochlear implant involves a lifetime commitment to rehabilitation and also to maintaining the device in a functioning condition. This paper describes the Cambridge experience of maintaining the Ineraid cochlear implant in a series of 25 patients over a 4 year period. On average, maintenance (repair of replacement) of components was required every 2.3 months of implant use, although some minor variations were noted between patients, and between component type. This rate of failure is sufficient to cause an Implant Centre to consider provision for repairs and holding of spare stock. It should be remembered that each breakdown returns the patient to a deafened state, albeit temporarily, but this can cause significant distress.

Cochlear Implants↗

PubMed1982

[Contribution with regard to the standardization of the terminology, the data and the rehabilitation program in cochlear implant research].

In the Field of Cochlear Implant Research the new terms are presented in a number of different ways. Further the achieved results have been based on varying data, making a comparison extremely difficult when not impossible. The contributors to this publication attempt to standardize the terminology, electrical data, and the evaluation of the hearing result, in order to achieve an objective comparison.

Audiometry↗

PubMed2003

Cochlear implantation in patients with auditory neuropathy of varied etiologies.

OBJECTIVES/HYPOTHESIS: Auditory neuropathy is a relatively recently described pattern of hearing loss characterized by preservation of outer hair cell function despite absent brainstem auditory evoked responses. Intact outer hair cell function is demonstrated by the presence of otoacoustic emissions and/or a measurable cochlear microphonic on electrocochleography, whereas no synchronous neural activity (absent action potentials) is seen on acoustically evoked brainstem auditory evoked response testing. The study reviews the authors' experience with six patients diagnosed with auditory neuropathy, four of whom have undergone cochlear implantation. MATERIALS AND METHODS: A retrospective review of all medical and audiological charts at the University of Virginia Hospitals (Charlottesville, VA) was performed to identify patients who have undergone cochlear implantation or have been diagnosed with auditory neuropathy, or both. RESULTS: Six patients with hearing loss attributable to auditory neuropathy were identified, four of whom have undergone cochlear implantation. Causes varied, including congenital, infectious, and idiopathic origins. Adults demonstrated subjective auditory perception on promontory stimulation, whereas no repeatable brainstem auditory evoked response waveforms could be demonstrated on pediatric promontory stimulation testing. Patients with implants demonstrated implant-evoked brainstem auditory evoked responses and improved audiological performance. CONCLUSIONS: The six cases presented in the study represent varied causes and, probably, varied sites of lesions of auditory neuropathy. Promontory stimulation has been valuable, particularly in adults. Cochlear implantation allows the opportunity to provide a supraphysiological electrical stimulation to the auditory nerve, with the hope of reintroducing synchronous neural activity. Greater confidence and enthusiasm for cochlear implantation in appropriately selected patients with auditory neuropathy are gained through experience with such diverse cases.

Adult↗

PubMed2004

[Poznań's program of cochlear implantation: 10 years experience].

The first cochlear implant in the ENT Department in Poznań was introduced in adult patient in January 1994. One year later the first deaf child was implanted. During 10 years over 200 deaf people were operated on. Modifications of diagnostics, surgery and rehabilitation were presented. Lowering the age of the implantation, changes of audiological criteria, genetic diagnostic and possibility of implantation in multi-handicapped patients were emphasized. Almost all surgeries were performed through the posterior tympanotomy and in one cases through the middle fossa approach. In one child with total ossification in CT scans Nucleus Double Array was used. Speech rehabilitation bases on auditory-verbal therapy. Rehabilitation consists of individual sessions with speech therapist and group therapy. Logorytmics exercises were introduced.

Catchment Area, Health↗

PubMed2006

Opinions on cochlear implant use in senior MED-EL patients.

This study assessed the subjective benefits of cochlear implants in senior patients wearing a MED-EL device. Data was compared with previous studies to assess the influence of recent speech-coding strategies and behind-the-ear speech processors; users of the behind-the-ear device and the body-worn device were also compared. An adaptation of the Nucleus 22-channel survey was sent to 141 cochlear implant users. The survey assesses perception of the device, communication benefits, handling the device and quality of life. Ninety-five surveys were returned. Results demonstrate that advanced technology provides greater benefit now than 9-13 years ago, notably: improved listening across noise, better understanding on the telephone and better speech perception. Users of the behind-the-ear device did not report more difficulties than body-worn device users but demonstrated better performance. Results show a positive outcome for cochlear implantation in a MED-EL seniors group.

Age Factors↗

PubMed2006

The cochlear implant electrode-pitch function.

The cochlear frequency-place function in normal hearing ears has been found to be an exponential relationship in a wide variety of species [D.D. Greenwood, J. Acoust. Soc. Am. 87 (1990) 2592-2605]. Although it seems reasonable to assume a similar function for electrical stimulation by means of an intra-cochlear electrode array, the exact frequency-place function for this special type of stimulation needs to be investigated. Six users of the MED-EL COMBI 40+ cochlear implant device with moderate to profound hearing loss between 125 and 1000 Hz in the non-implanted ear took part in a binaural pitch adjustment experiment. The COMBI 40+ electrode array provides a deep insertion into the scala tympani and a wide spatial separation between the stimulating electrodes. Insertion depth was controlled by Stenver's view plain radiographs and the insertion angle was estimated. The task of the subjects was to adjust the frequency of a sinusoid presented in the non-implanted ear by means of an adjusting knob until they perceived the same pitch as was elicited by a reference stimulus in the implanted ear. The results show adjustments corresponding to electrode positions along the cochlea, with the exception of the two most apical electrodes for most of the subjects. Pitch increased in an orderly fashion with an average of 98 Hz per electrode separation (40 Hz/mm). In contrast to the exponential predictions according to [D.D. Greenwood, J. Acoust. Soc. Am. 87 (1990) 2592-2605] for normal hearing, the average electrode-pitch function shows a linear relationship.

Adult↗