Voice fundamental frequency differences and speech recognition with noise and speech maskers in cochlear implant recipients.

Cochlear implant (CI) recipients are limited in their perception of voice cues, such as the fundamental frequency (F0). This has important consequences for speech recognition when several talkers speak simultaneously. This examination considered the comparison of clear speech and noise-vocoded sentences as maskers. For the speech maskers it could be shown that good CI performers are able to benefit from F0 differences between target and masker. This was due to the fact that a F0 difference of 80 Hz significantly reduced target-masker confusions, an effect that was slightly more pronounced in bimodal than in bilateral users.

Expanding unilateral cochlear implantation criteria for adults with bilateral acquired severe sensorineural hearing loss.

OBJECTIVES: To report on a retrospective cohort study on the effects of expanding inclusion criteria for application of cochlear implants (CIs) on the performance 1-year post-implantation. METHODS: Based on pre-implantation audiometric thresholds and aided speech recognition scores, the data of 164 CI recipients were divided into a group of patients that fulfilled conservative criteria (mean hearing loss at 0.5, 1 and 2 kHz > 85 dB HL and phoneme scores with hearing aids < 30%), and the remaining group of patients that felt outside this conservative criterion. Speech recognition scores (in quiet) and quality of life (using the NCIQ) of both groups, measured at 1-year post-implantation, were compared. RESULTS: The group that felt outside the conservative criterion showed a higher phoneme score at 1-year post-implantation compared to the conservative group, suggesting that relaxed criteria have a positive influence on the speech recognition results with CI. With respect to quality of life, both groups significantly improved 1-year post-implantation. The conservative group showed a higher benefit on the advanced perception domain of the NCIQ. Based on their worse pre-implantation hearing, this was expected. CONCLUSIONS: The data suggest that relaxation of CI indication positively affects the speech recognition performance of patients with severe hearing loss. Both groups of patients showed a positive effect of CI on the quality of life. This benefit relates to communication skills and the subjective day-to-day functioning in society.

A practical guide to cochlear implantation in adults with long durations of monaural sound deprivation.

OBJECTIVE: This paper aims to summarize published findings by the authors and integrate these within current literature to support clinical guidelines when choosing an ear for cochlear implantation in adults with long-term monaural sound deprivation. STUDY SAMPLE: Four retrospective cohort studies based on data collected in five cochlear implantation centres with adults with bilateral hearing loss who used a single hearing aid for at least 15 years prior to unilateral or bilateral cochlear implantation. DESIGN: Review, integration and interpretation of retrospective cohort studies to support clinical recommendations. RESULTS: In this population, the prelingual nature of the hearing loss and the duration of bilateral significant hearing loss were the most reliable predictors of cochlear implantation outcomes. Importantly, the duration of sound deprivation in the ear to be implanted was not a significant predictor of speech recognition scores after cochlear implantation and should carry less weight in making recommendations. CONCLUSIONS: In most adults with postlingual hearing loss and long-term monaural sound deprivation, the sound-deprived sound deprivation ear should be preferred for implantation. For adults with prelingual deafness and monaural sound deprivation, the decision should weigh the risks of obtaining poorer results with the cochlear implant compared to the benefits of accessing binaural hearing.

Evidence-based guidelines for recommending cochlear implantation for young children: Audiological criteria and optimizing age at implantation.

OBJECTIVE: Establish up-to-date evidence-based guidelines for recommending cochlear implantation for young children. DESIGN: Speech perception results for early-implanted children were compared to children using traditional amplification. Equivalent pure-tone average (PTA) hearing loss for cochlear implant (CI) users was established. Language of early-implanted children was assessed over six years and compared to hearing peers. STUDY SAMPLE: Seventy-eight children using CIs and 62 children using traditional amplification with hearing losses ranging 25-120 dB HL PTA (speech perception study). Thirty-two children who received a CI before 2.5 years of age (language study). RESULTS: Speech perception outcomes suggested that children with a PTA greater than 60 dB HL have a 75% chance of benefit over traditional amplification. More conservative criteria applied to the data suggested that children with PTA greater than 82 dB HL have a 95% chance of benefit. Children implanted under 2.5 years with no significant cognitive deficits made normal language progress but retained a delay approximately equal to their age at implantation. CONCLUSIONS: Hearing-impaired children under three years of age may benefit from cochlear implantation if their PTA exceeds 60 dB HL bilaterally. Implantation as young as possible should minimize any language delay resulting from an initial period of auditory deprivation.

Evidence-based guidelines for recommending cochlear implantation for postlingually deafened adults.

OBJECTIVE: Adult selection criteria for cochlear implantation have been developed based on analysis of the post-operative performance of a large group of postlingually deafened adults. Original criteria published in 2004 were reviewed and amended to reflect outcomes currently being achieved by implant recipients. DESIGN: Retrospective review of 12-month post-operative speech perception performance of adults implanted at the Eye and Ear Hospital, Melbourne, Australia. STUDY SAMPLE: A total of 382 postlingually deafened adults, using a Freedom, Nucleus 5, or CI422 Slim Straight cochlear implant were used to create a comparative set of data. RESULTS: Revised guidelines suggest that adults with postlingual hearing loss can now be considered cochlear implant candidates if they obtain scores of up to 55% for open-set phonemes in quiet in the ear to be implanted. Functional benefit may vary depending on the recipients' contralateral hearing. CONCLUSIONS: This study supports the provision of cochlear implants to candidates with significant residual hearing when at least one ear meets the criterion outlined above. Patient-specific counseling is required to ensure the potential to benefit predicted by the current model is acceptable to the individual patient and their family. Counseling regarding functional benefit must take into consideration hearing in the contralateral ear.

[The Heidelberg CI database module : Quality control in hearing restoration with cochlear implants]. / Das Heidelberger CI­Datenbankmodul : Qualitätssicherung in der Cochleaimplantatversorgung.

BACKGROUND: Cochlear implants (CI) have been established as the therapy of choice for functional deafness. The number of CI-rehabilitated patients is continuously growing. The resulting data can provide important information for physicians, health insurance companies, and scientists. Assessment and structuring of data becomes more feasible with the application of modern database systems. MATERIALS AND METHODS: In collaboration with Innoforce Est., Liechtenstein, the authors developed a database module for the specific needs of CI patients. Data of 100 patients were included and evaluated. The main features of the module and an example data analysis are presented. RESULTS: Analysis of data from these 100 patients reveals 50 men and 50 women aged between 1 and 87 years, with a maximum value in the 51-60-years age group. More than 50% of the patients were also severely hearing impaired in the contralateral ear and fitted the CI indication criteria. Functional deafness in the ear subsequently fitted with CI in most of the patients had arisen more than 20 years previously. Preoperative diagnostic electrical stimulation of the cochlear nerve was positive in 67 patients. All 100 patients perceived auditory sensations with the CI. CONCLUSION: The presented patient cohort is representative of patients at the Department of Otorhinolaryngology, University of Heidelberg Medical Center, Germany, and the demographic distribution is in accordance with the literature. The state of the contralateral ear, often also fitting the CI indication, is not surprising, as cochlear implantation is a comparatively new procedure. Preoperative electrical stimulation turned out not to be significant by itself. The hearing results and overview of complications were easy to calculate in comparison to a pure data storage system such as i.s.h.med.

Cochlear implant programming: a global survey on the state of the art.

The programming of CIs is essential for good performance. However, no Good Clinical Practice guidelines exist. This paper reports on the results of an inventory of the current practice worldwide. A questionnaire was distributed to 47 CI centers. They follow 47600 recipients in 17 countries and 5 continents. The results were discussed during a debate. Sixty-two percent of the results were verified through individual interviews during the following months. Most centers (72%) participated in a cross-sectional study logging 5 consecutive fitting sessions in 5 different recipients. Data indicate that general practice starts with a single switch-on session, followed by three monthly sessions, three quarterly sessions, and then annual sessions, all containing one hour of programming and testing. The main focus lies on setting maximum and, to a lesser extent, minimum current levels per electrode. These levels are often determined on a few electrodes and then extrapolated. They are mainly based on subjective loudness perception by the CI user and, to a lesser extent, on pure tone and speech audiometry. Objective measures play a small role as indication of the global MAP profile. Other MAP parameters are rarely modified. Measurable targets are only defined for pure tone audiometry. Huge variation exists between centers on all aspects of the fitting practice.

[Auditory neuropathy (auditory neuropathy spectrum disorders): the approaches to diagnostics and rehabilitation].

Auditory neuropathies (auditory neuropathy spectrum disorders, ANSD) may be a consequence of dysfunction of inner hair cells and/or of synapses between these cells and auditory nerve fibers. Another cause of these disorders is supposed to be pathological changes in the auditory nerve itself. The outcome of the rehabilitative treatment of the patients presenting with this disorder depends on the quality of diagnosis and precise location of the pathological process. The present study involved 82 patients with auditory neuropathies. The audiological data obtained in the course of this work were compared with the results of other authors published during the recent years. The objective audiological examination included electrocochleography, registration of auditory brainstem response (ABR) and otoacoustic emission of short-latency and long-latency evoked auditory nerve action potentials. High-amplitude cochlear microphonic and transient evoked otoacoustic emission (TEOAE) potentials were recorded in 82 patients. In 17 (20.7%) patients, otoacoustic emission disappeared in the course of time even though the microphonic potential remained stable. It was shown that the results of electrical acoustic correction in the patients exhibiting long-latency evoked auditory action potentials and positive ABR to electrical stimulation (positive promontory test) were better than in the remaining cases. The outcome of cochlear implantation to a large extent depended on the localization of the pathological process. Specifically, the results of the treatment of the patients with high-amplitude summation potentials, prolonged latency, and positive auditory action potentials in response to electrical stimulation (typical of pre-synaptic localization of the pathological process) were better than in the patients with normal summation potentials, pathological auditory nerve action potentials, TEOAE, and negative ABR to electrical stimulation (indicative of post-synaptic localization of the pathological process). In the latter group of patients, the results of cochlear implantation were far from being satisfactory. It is concluded that additional information facilitating categorization of the pathological process can be obtained by the identification of the genetic mutations responsible for the development of auditory neuropathies.

[The effectiveness of rehabilitation following bilateral cochlear implantation].

The Russian Federation similar to many other countries witnesses the continuous rise in the number of patients undergoing bilateral cochlear implantation. The objective of the present study was to estimate the effectiveness of rehabilitation following bilateral cochlear implantation. A total of 28 patients admitted to the Russian Research and Practical Centre of Audiology and Hearing Rehabilitation between 2011 and 2012 were available for the examination with the use of tonal threshold audiometry. Twenty one patient underwent sequential cochlear implantation, simultaneous implantation was effected in the remaining 7 ones. The patients were tested by a speech therapist. The tonal threshold audiometry in the free sound field showed that the auditory thresholds corresponded to grade I hearing impairment. Free-field sound perception threshold in the bilaterally implanted patients with two active speech processors was significantly better than in those having one speech processor. All the patients exhibited binaural summation effect. Surdopedagogical testing revealed positive dynamics of the speech development. The positive dynamics was especially well apparent pronounced in the patients operated simultaneously or when the period between two implantations did not exceed 1 year. A reduction of the duration of the period between two surgical interventions resulted in the decreased difference between sound perception in two ears, improvement of sound localization, and acceleration of speech development. All the patients showed good speech recognition in the complex acoustic environment and the ability to locate sounds.

[The experience of the work of a regional cochlear implantation center].

The objective of the present study was to determine the main lines of the development of a regional cochlear implantation centre and to estimate the effectiveness of rehabilitation of the children treated with the use of cochlear implantation. Analysis of the results of the work of the branch of the Russian Research and Practical Centre of Audiology and Hearing Rehabilitation based at Voronezh Regional Children's Clinical Hospital No 1 provided materials for the establishment of the principle directions of activities of the regional cochlear implantation centre where a total of 161 children have been kept under observation during the last years. Fifty six of the 138 children at the age varying from 1 to 12 years were given the surgical treatment. The patients were followed up within two and more years after connection of the speech processor. The study group was comprised only of the pre-lingually deaf children. It is concluded that the performance of most cochlear implantation procedures based at local centres allows to reduce the cost of rehabilitation and makes the high-tech medical aid more readily available to the patients; moreover, the practical introduction of remote speech processor programming software into the work of regional cochlear implantation centres enhances the effectiveness of the rehabilitative measures based at local medical facilities.

[The evolution of surgical interventions for cochlear implantation at the Russian Research and Practical Centre of Audiology and Hearing Rehabilitation].

The objective of the present study was to estimate and analyse the effectiveness and labour intensity of the methods of surgical intervention for cochlear implantation. The analysis of the surgical stage of cochlear implantation was based on the examination of 2073 children and adults during the period from 1991 to 2013. The age of the patients varied between 6 months to 71 years. The cause of deafness was meningitis and an injury in 11% and 6% of the patients respectively. The cochlear implants from Advanced Bionics were inserted in 495 patients, those from Med-El in 9 ones , and from Neurelec in 20, and Nucleus devices from Cochlear in the remaining patents (n=1549) including 37 double-array electrodes and a Hybrid implant for electroacoustic correction of hearing . The implants with a straight and perimodiolar electrode were placed in a roughly equal number of the patients. The rationale for the performance of selected components of the surgical stage of cochlear implantation was developed along with the technical procedures for the purpose applied at this Centre since 1991. The original methods for the fixation and covering of the receiver-stimulator and also for the choice of the place of the electrode array insertion into the cochlea are described. They allowed to significantly decrease the frequency of complications, duration and extent of the surgical intervention as well as to reduce to a minimum post-operative manipulations.

[The current tendencies and prospects of the neural response telemetry in the rehabilitation of the patients after cochlear implantation].

The objective of the present study was to estimate the potential of the modern technique for telemetry of the neural response during rehabilitation of the patients following cochlear implantation. The methods for the purpose included comparison of the results of intra- and postoperative registration on neural response telemetry (NRT) and evaluation of the influence of perimodiolar localization of electrodes of cochlear implants on the threshold level of stimulation and propagation of excitation inside the cochlea. The results of the study confirm the possibility of using the registration of the electrically evoked auditory nerve potential for fitting the speech processor of the cochlear implant. In addition, it was shown that the application of the perimodiolar electrode significantly narrows the intracochlear excitation distribution profile which enhances the rehabilitative effectiveness of cochlear implantation.

[Cochlear implantation in immunocompromised patients].

This paper reports a clinical case that gives evidence of the possibility of cochlear implantation after liver transplantation. Patient K. aged 3 years 10 months was admitted to the Russian Research and Practical Centre of Audiology and Hearing Rehabilitation with the diagnosis of type IB glycogenosis after maternal liver transplantation associated with chronic neutropenia, chronic cutaneous and mucosal infection, partial symptomatic partial epilepsy, retarded psycho-motor development, and complaints of the absence of auditory response. The audiological examination provided materials for the diagnosis of grade IV bilateral sensorineural hearing loss tending toward deafness. Cochlear implantation recommended to the patient was performed on February 20, 2013 using the HiRes 90 K implant with the HiFocus Helix electrode (Advanced Bionics, USA). The surgical intervention and the postoperative period passed without complications. The speech processor was activated one month after surgery. The results of surdopedagogical testing gave evidence of successful rehabilitation promising the further improvement. It is concluded that immunosuppressive therapy is not an absolute contraindication for cochlear implantation, but this procedure requires detailed examination and thorough preparation for the forthcoming surgery.

Feasibility of real-time selection of frequency tables in an acoustic simulation of a cochlear implant.

OBJECTIVES: Perception of spectrally degraded speech is particularly difficult when the signal is also distorted along the frequency axis. This might be particularly important for post-lingually deafened recipients of cochlear implants (CIs), who must adapt to a signal where there may be a mismatch between the frequencies of an input signal and the characteristic frequencies of the neurons stimulated by the CI. However, there is a lack of tools that can be used to identify whether an individual has adapted fully to a mismatch in the frequency-to-place relationship and if so, to find a frequency table that ameliorates any negative effects of an unadapted mismatch. The goal of the proposed investigation is to test the feasibility of whether real-time selection of frequency tables can be used to identify cases in which listeners have not fully adapted to a frequency mismatch. The assumption underlying this approach is that listeners who have not adapted to a frequency mismatch will select a frequency table that minimizes any such mismatches, even at the expense of reducing the information provided by this frequency table. DESIGN: Thirty-four normal-hearing adults listened to a noise-vocoded acoustic simulation of a CI and adjusted the frequency table in real time until they obtained a frequency table that sounded "most intelligible" to them. The use of an acoustic simulation was essential to this study because it allowed the authors to explicitly control the degree of frequency mismatch present in the simulation. None of the listeners had any previous experience with vocoded speech, in order to test the hypothesis that the real-time selection procedure could be used to identify cases in which a listener has not adapted to a frequency mismatch. After obtaining a self-selected table, the authors measured consonant nucleus consonant word-recognition scores with that self-selected table and two other frequency tables: a "frequency-matched" table that matched the analysis filters with the noisebands of the noise-vocoder simulation, and a "right information" table that is similar to that used in most CI speech processors, but in this simulation results in a frequency shift equivalent to 6.5 mm of cochlear space. RESULTS: Listeners tended to select a table that was very close to, but shifted slightly lower in frequency from the frequency-matched table. The real-time selection process took on average 2 to 3 min for each trial, and the between-trial variability was comparable with that previously observed with closely related procedures. The word-recognition scores with the self-selected table were clearly higher than with the right-information table and slightly higher than with the frequency-matched table. CONCLUSIONS: Real-time self-selection of frequency tables may be a viable tool for identifying listeners who have not adapted to a mismatch in the frequency-to-place relationship, and to find a frequency table that is more appropriate for them. Moreover, the small but significant improvements in word-recognition ability observed with the self-selected table suggest that these listeners based their selections on intelligibility rather than some other factor. The within-subject variability in the real-time selection procedure was comparable with that of a genetic algorithm, and the speed of the real-time procedure appeared to be faster than either a genetic algorithm or a simplex procedure.

Consonant development in pediatric cochlear implant users who were implanted before 30 months of age.

This study provided a yearly record of consonant development for the initial 4 years of cochlear implant (CI) use and established a precedent for using a standardized articulation test, the Goldman-Fristoe Test of Articulation-2 (Goldman, R., & Fristoe, M. [2000]. Goldman-Fristoe Test of Articulation-2. Circle Pines, MN: American Guidance Services). The study used CI age as a referent for 32 children who received their CI before 30 months of age. Consonants produced by 70% of the children were listed, as were the most common error types, which were consonant omissions and substitutions. Using consonant repertoire lists and standard scores, the study revealed that children with CIs had acquisition patterns that were similar to their peers when the duration of CI experience was similar to the chronological age norms of typically developing children. The results revealed that CI users need time to coordinate their articulatory organizing principles with the input they receive from their CI. It is appropriate to use length of CI use as a proxy for chronological age during the first 4 years when comparing articulation development with hearing peers.

Electrophysiologic and behavioral outcomes of cochlear implantation in children with auditory nerve hypoplasia.

OBJECTIVES: Hypoplasia of the auditory nerve (AN) refers to significant narrowing of the VIIIth cranial nerve which could compromise stimulation of the nerve by electrical pulses delivered from a cochlear implant (CI), thereby hindering activity in other parts of the auditory pathways. To compensate, high current levels or increased charge may be required to elicit auditory perception causing current to spread to other cranial nerves and potentially resulting in unwanted myogenic responses. Deficits in central auditory activity could reduce perception of speech and language. In the present study, we measured auditory brainstem responses in children with and without hypoplasia of the AN to answer the following questions. In children with hypoplastic ANs, (a) can CI stimulation evoke typical patterns of activity from the AN and brainstem?, (b) do brainstem responses change with CI experience?, (c) are evoked responses dependent on the size of the AN pathway?, and (d) does auditory development measured by behavioral tests of speech perception develop more slowly than in peers with normal AN diameter? DESIGN: Of 807 children using CIs in our program, 20 (2.5%) were identified as having AN hypoplasia using high-resolution computed tomographic scan and/or magnetic resonance imaging. An age-matched control group of children using CIs with normal AN diameter were recruited to compare electrophysiological and behavioral measures. Radiologic imaging was used to measure the diameter of the internal auditory canal (IAC), auditory nerve canal (ANC), and AN. Electrophysiological testing of the evoked compound action potential and auditory brainstem response was performed at CI activation and every 3 mo after initial testing up to 2 yr. Peak latency and waveform morphology were compared between study and control groups. Tests of speech perception and discrimination were attempted every 12 mo after device activation up to 10 yr. RESULTS: : Hypoplastic AN was identified as moderate to critical stenosis of the IAC, ANC, and AN. Initial electrically evoked compound action potential responses were mostly absent in children with AN hypoplasia. In the time window when electrically evoked auditory brainstem responses would be expected, some responses included single amplitude peaks at normal wave eV latencies, but the majority were abnormal, with peaks at atypical latencies or with no observable wave peaks. All evoked responses were inconsistent over time and did not reflect a typical pattern of auditory brainstem development. Speech perception scores were significantly poorer in the study group compared with controls and did not improve with CI experience. The type of abnormal evoked waveform response was independent of IAC, ANC, or AN diameter and also independent of behavioral outcome measures. CONCLUSIONS: : Evoked responses recorded in CI children with AN hypoplasia indicate a high incidence of nonauditory activity with CI use. The range of abnormal responses was not predicted by the severity of the hypoplastic AN or associated structures. This, along with poorer auditory development compared with peers with normal AN diameters, suggests that children with hypoplasia of the AN are poor candidates for cochlear implantation.

[A comparison of the long-term efficacy of cochlear implantation at early and late age]. / Erken ve geç yas koklear implant uygulamasinda uzun dönem etkinliklerinin karsilastirilmasi

OBJECTIVES: This study aims to investigate the effects of age factor on the long-term efficacy of cochlear implantation. PATIENTS AND METHODS: The electronic records of patients, who underwent cochlear implantation with the initial diagnosis of bilateral severe to profound sensorineural hearing loss in our clinic between January 2001 and December 2008, were analyzed retrospectively. The patients were divided into two groups according to their age at the time of cochlear implantation, including group 1 with the patients less than four years of age and group 2 with the patients more than four years of age. Groups were evaluated and compared for the in terms of demographic characteristics, Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) at three years following surgery. RESULTS: A total of 37 patients underwent cochlear implantation. Of them, 18 patients (48.6%) were operated at less than four years of age, while 19 patients (51.4%) were operated at more than four years of age. No significant difference was found between the groups in terms of sex, educational level and profession of the parents, operated side and duration of implant use. According to CAP and SIR categories, group 1 patients had statistically significantly higher level of the CAP and SIR categories (p=0.009 and p<0.001 respectively). CONCLUSION: Our study results suggested that the age of cochlear implantation has significant effects on long-term hearing and speech abilities. Cochlear implantation carried out at earlier ages (<4) enhances more satisfactory results in terms of long-term efficacy.

[The algorithms for the tuning of the speech processors of cochlear implants].

The tuning of the speech processors of cochlear implants implies the measurement of the threshold perception levels and the achievement of the maximally comfortable level of loudness in each auditory channel. The authors present a detailed description of the approach to the optimal tuning including the sequence of procedures and manipulations for this purpose, from the first tuning to the achievement of the desired result. This algorithm summarizes the worldwide and the authors' own experience based on the original investigations that have been carried in the Sankt-Peterburg Research Institute of Otorhinolaryngology and Speech during more than 15 years.

Statistical analysis and interpretation in a follow-up study of prelingually deaf children implanted before 5 years of age.

PROBLEMS: One important challenge in the follow-up study was the need to develop composite measures that were highly reliable and equally representative of communication skills measured at two distinct developmental periods. A second challenge was the need to partition variance in the outcome variables among conceptually important sets of variables in an attempt to identify unique and significant predictors and to identify likely pathways of influence. A final challenge was the need to preserve sample size in the presence of attrition from the initial data collection period and missing data. SOLUTIONS: Primary analyses were based on principal components analysis to form composite measures of highly correlated variables followed by hierarchical multiple regression to determine the contribution of predictor sets ordered to reflect important causal assumptions and conceptual questions. The principal components analyses resulted in unidimensional, highly reliable composite measures of communication skill, educational environment, and information processing. The hierarchical multiple regression analyses allowed partitioning variance to isolate the unique contributions made by particular variables or sets of variables. Importantly, these analyses also allowed inferences about pathways of influence from early predictors to later outcomes. Multiple imputation was used to construct complete data sets, preserving power and consistency across the numerous analyses. SUMMARY: Collectively, the chosen statistical analyses provide a pragmatic and parsimonious solution to the challenges posed by the data collected in this study. The analyses allowed clear conclusions about the major predictors of early and late communication skill in this sample and identified likely pathways through which early child, family, and educational environment variables have their influence.