Performance of prelingually and postlingually deaf patients using single-channel or multichanel cochlear implants

The auditory and aided lipreading performance of 8 prelingually and 11 postlingually deaf patients who had received a single-channel or multichannel cochlear implant was evaluated during 2 years of follow-up. Although all the patients improved on both closed-set pattern recognition and speech drimination tests and on a Continouous Discourse Tracking task, the most significant improvement was observed in the postlingually deaf patients who were using a multichannel implant. These patients were the only ones to achieve open-set speech recognition in the auditory-only condition. Only small differences were found between prelingually deaf patients who were using a single-channel system and those who were using a multichannel system. The users' evaluations, obtained by means of a questionnaire, were generally positive in all patients. Based on the study results, the authors concluded that it is feasible to use cochlear implants in highly motivated prelingaully deaf patients who have learned to use oral-aural communication.     

Clinical results with a hearing aid and a single-channel vibrotactile device for profoundly deaf adults

The speech perception of a group of 19 adults with post-lingual profound to total hearing loss was tested with nine closed-set speech tests without lipreading, two open-set tests without lipreading and two open-set speech tests with lipreading. The subjects were all prospective cochlear implant patients participating in a clinical trial of the implant and the results reported here were obtained as part of the pre-operative assessment. They were divided into groups on the basis of their prior experience with the aid(s), their speech detection thresholds with the two aids and their personal preferences. Seven of the subjects used a hand-held single-channel vibrotactile device and the other 12 used a powerful conventional hearing aid. Subjects from each group scored significantly better than chance on the closed set tests without lipreading. Training or regular hearing aid use was correlated with good performance on the closed-set tests. No subject showed a significant improvement of the lipreading score when the aid was used as a supplement. The use of sophisticated wearable tactile devices and extensive training may allow a better result, but in this clinical program, neither a hearing aid nor a single-channel vibrotactile device greatly benefited the postlingually profoundly deaf adults.     

Vibrotactile perception of segmental features of speech: a comparison of single-channel and multichannel instruments

This experiment compared the recognition performance of artificially deafened listeners for segmental stimuli presented through a single-channel tactile device and through a 24-channel vocoder. Both consonant and vowel stimuli were tested under visual only, tactile only, and visual + tactile conditions. Each subject received a pretest, eight 2-hr training sessions, and a posttest. Results indicated no significant differences between subject's overall recognition performance with two different tactile devices. Analysis of consonant confusions showed that both devices transmit the features of voicing, manner, and place of articulation in a similar fashion. In contrast to an earlier study on suprasegmental features by Carney and Beachler (1986), these results do not support the notion that preservation of the waveform envelope of speech is necessary for the transmission of segmental features of speech. These results also suggest that tactile perception of segmental features may not be altered significantly by the tactile array chosen.     

Auditory perception changes after reimplantation in a child cochlear implant user.

The ability to remove cochlear implants from children and subsequently reimplant a more complex device in the same ear was the concern of this single case study. A postlinguistically deafened child, J.L., received a single-channel cochlear implant 1 yr after contracting meningitis and suffering a profound bilateral sensorineural hearing loss. After 3 yr of successful implant use, J.L. suffered an internal coil failure. She was then explanted and reimplanted with a multichannel cochlear implant in the same ear. This case report details her speech perception skills with her single-channel cochlear implant, a vibrotactile aid, and a multichannel cochlear implant. Results from auditory perceptual measures suggest that the explantation/reimplantation process was technically feasible with no adverse effects on J.L.'s ability to utilize a more sophisticated device and to exceed her previous performance levels.     

Open-set word recognition with the 3M/Vienna single-channel cochlear implant

The author visited Innsbruck (Austria) to evaluate the performance of nine of the better patients implanted in Europe with the 3M/Vienna single-channel cochlear implant. Word- and sentence-level speech recognition tests recorded in German by two speakers from Austria were presented. Performance varied from 15% to 86% correct word recognition on the sentence material, 11% to 57% correct word recognition with word lists, and 21% and 66% correct phoneme recognition on the word tests. These results confirm earlier studies indicating that high levels of open-set word recognition without visual cues can be obtained with the 3M/Vienna single-channel cochlear implant.     

Audiological performance with cochlear reimplantation from analogue single-channel implants to digital multi-channel devices.

Cochlear implantation has been performed for almost two decades at the Vienna University Hospital. Until 1994, single-channel implants were used (Ball-Electrode, SC6/2SC6, Vienna/Epoxy, Med-E1, Innsbruck, Austria). The development of multi-channel devices (Combi 40/40+), which provide significantly improved speech recognition performance, led to the reimplantation of some patients who had previously received single-channel implants. It was of particular interest to find out if there was a deterioration of the central "learning process" by the reimplantation from the analogue single-channel device to the tonotopic pulsatile multi-channel stimulation. In this study, we attempted to demonstrate that single-channel implants have an impact on the neural organisation of the auditory system. Two groups of post-lingually deaf adult patients were tested. Group A had previously received single-channel implants and were reimplanted with the new Combi 40/40+ cochlear implant (Med-E1, Innsbruck, Austria) in the same ear. Group B was implanted only with the Combi 40/40+. Six different speech recognition tests were subsequently performed on all patients, and the two groups performed similarly. Furthermore, it was discovered that group A obtained significant speech recognition improvement (p<0.05) with monosyllabic words and number tests 1 month following reimplantation.     

Evaluations of 3M/House single-channel and nucleus multichannel cochlear implants.

3M/House single-channel (n = 158) and Nucleus multichannel (n = 71) adult cochlear implant users were surveyed about their devices. In comparison to the 3M/House users, the Nucleus users reported better speech and environmental sounds perception and more hours of daily use. However, Nucleus users also were more likely to report that the expense of upkeep and frequent movement of external parts of their implants were problems. On average, users in both groups were satisfied and felt that their implants had positively affected their lifestyle, enjoyment of social events, and employability. Differences between groups regarding these variables were not found. Multiple regression indicated that the users' ratings of the effects of their implants on speech perception, environmental sounds perception, enjoyment of social events, and lifestyle were all statistically significant predictors of satisfaction. It was concluded that the majority of the users in either group thought their devices provided real-world benefits.     

Speech understanding in quiet and noise in bilateral users of the MED-EL COMBI 40/40+ cochlear implant system

OBJECTIVE: The purpose of the study was to investigate speech understanding in quiet and noise in subjects bilaterally implanted with multi-channel cochlear implants. DESIGN: Nine adults bilaterally implanted with MED-EL implants were included in the study. The subjects were tested in three conditions: with both implants, with the right implant only, and with the left implant only. Speech tests included monosyllables in quiet and sentences in noise (10 dB signal to noise ratio). Speech was presented from the front, and noise was presented from either 90 degrees or 270 degrees azimuth. RESULTS: All subjects reported benefit from bilateral stimulation. Speech scores for all subjects were higher with bilateral than with unilateral stimulation. The average score across subjects for sentence understanding was 31.1 percentage points higher with both cochlear implants compared with the cochlear implant ipsilateral to the noise, and 10.7 percentage points higher with both cochlear implants compared with the cochlear implant contralateral to the noise. The average score for recognition of monosyllabic words was 18.7 percentage points higher with both cochlear implants than with one cochlear implant. All of these differences in average scores were significant at the 5% level. CONCLUSIONS: Bilateral cochlear implantation provides a significant benefit in speech understanding in both quiet and noise.     

Measuring listening effort expended by adolescents and young adults with unilateral or bilateral cochlear implants or normal hearing

Abstract

Objectives

To compare the listening effort expended by adolescents and young adults using implants versus their peers with normal hearing when these two groups are achieving similar speech perception scores. The study also aimed to compare listening effort expended by adolescents and young adults with bilateral cochlear implants when using two implants versus one.

Methods

Eight participants with bilateral cochlear implants and eight with normal hearing aged 10–22 years were included. Using a dual-task paradigm, participants repeated consonant–nucleus–consonant (CNC) words presented in noise and performed a visual matching task. Signal-to-noise ratios were set individually to ensure the word perception task was challenging but manageable for all. Reduced performance on the visual task in the dual-task condition relative to the single-task condition was indicative of the effort expended on the listening task.

Results

The cochlear implant group, when using bilateral implants, expended similar levels of listening effort to the normal hearing group when the two groups were achieving similar speech perception scores. For three individuals with cochlear implants, and the group, listening effort was significantly reduced with bilateral compared to unilateral implants.

Discussion

The similar amount of listening effort expended by the two groups indicated that a higher signal-to-noise ratio overcame limitations in the auditory information received or processed by the participants with implants. This study is the first to objectively compare listening effort using two versus one cochlear implant. The results provide objective evidence that reduced listening effort is a benefit that some individuals gain from bilateral cochlear implants.     

语前聋儿童人工耳蜗植入效果的评估

目的探索语前聋儿童人工耳蜗植入效果的评估方法.方法受试者为18名接受人工耳蜗植入的语前聋儿童,耳蜗植入时平均年龄6岁.按人工耳蜗使用时间长短分为四个阶段进行评估:第一阶段18名患儿,使用人工耳蜗1～12个月;第二阶段12名,使用人工耳蜗13～24个月;第三阶段8名,使用人工耳蜗25～36个月;第四阶段6名,使用人工耳蜗在36个月以上.描述性分析,以问卷的形式了解儿童在人工耳蜗植入后声音接受、言语表达及行为等方面的变化;言语测试,进行言语识别能力和发声能力测试.结果第一阶段患儿,能够感知和辨别来自家庭和环境中的声音;第二阶段患儿,封闭项词识别率是51%,开放项词识别开始启动;第三阶段患儿,封闭项词识别率达到72%,开放项词识别率是40%,能正确发出的单词数是42%;第四阶段患儿,封闭项词识别率和开放项词识别率分别达到84%和53%,能正确发出的单词数达62%,部分患儿已有自发的口语表达.结论人工耳蜗植入对语前聋患儿的言语发育有帮助,患儿的言语能力随着人工耳蜗使用时间的推移不断进步.     

Iowa cochlear implant clinical project: results with two single-channel cochlear implants and one multi-channel cochlear implant

Cochlear implants have become a realistic alternative for the management of profoundly deaf patients. A variety of implants with differing electrode designs and coding strategies have been developed by nine major implant centers around the world. Each center has their "star" patient, but objective comparisons between these different implant designs are unavailable. In order to determine the performance characteristics of the present generation of cochlear implants, comparison data are vital. We have developed an independent center where uniform objective comparisons of different cochlear implants can be performed longitudinally. This report will present results of nine patients implanted with three different cochlear implant prostheses. Four patients have been implanted with the Los Angeles (House) single-channel implant, three patients have received the Vienna (Hochmair) single-channel intracochlear device, and two patients have been implanted with the Melbourne (Clark) 21-channel unit. All patients have had 11 months or more of experience with their cochlear prostheses. The results of a comprehensive audiologic battery which includes audiovisual and environmental tasks are presented. All implants provide significant improvement in speechreading and sound awareness. The findings to date suggest that there is strong correlation between top-down cognitive processing (as reflected by lip reading skills) and performance with cochlear implants.     

A comparison of the growth of open-set speech perception between the nucleus 22 and nucleus 24 cochlear implant systems.

OBJECTIVE: To compare the short-term development of open-set speech perception between implementations of the spectral peak (SPEAK) strategy in adults using the Nucleus 22 (N22) Spectra processor and the Nucleus 24 (N24) system with the SPrint processor. STUDY DESIGN: Two sets of patients with a follow-up period of 3 months were compared. SETTING: This study was conducted at the New York University (NYU) Medical Center. PATIENTS: Thirty-six profoundly hearing-impaired adults were included in this study. INTERVENTION: Sixteen adults received the N22 cochlear implant with the Spectra speech processor and twenty adults received the N24 cochlear implant with the SPrint speech processor. MAIN OUTCOME MEASURES: Open-set speech perception for the patients with N22 implants was evaluated preoperatively and postoperatively using the following measures: NU-6 monosyllabic words, Iowa sentences, and CID sentences. CNC words, CUNY sentences, and HINT sentences were used to assess the patients with N24 implants. RESULTS: Results revealed that the N22 and N24 cochlear implant recipients had significant open-set speech recognition 3 and 6 months after implantation. The apparent favorable absolute scores for the patients with N24 implants were equalized when a multivariate analysis was performed to account for their younger age at time of implantation and shorter length of deafness. CONCLUSIONS: The growth of open-set word and sentence recognition in similar between the N22 and N24 cochlear implants. Longitudinal studies are needed to determine if higher ceiling scores are present in the N24. Further exploration of monopolar versus bipolar stimulation is warranted.     

Recognition of "real-world" musical excerpts by cochlear implant recipients and normal-hearing adults

OBJECTIVE: The purposes of this study were (a) to compare recognition of "real-world" music excerpts by postlingually deafened adults using cochlear implants and normal-hearing adults; (b) to compare the performance of cochlear implant recipients using different devices and processing strategies; and (c) to examine the variability among implant recipients in recognition of musical selections in relation to performance on speech perception tests, performance on cognitive tests, and demographic variables. DESIGN: Seventy-nine cochlear implant users and 30 normal-hearing adults were tested on open-set recognition of systematically selected excerpts from musical recordings heard in real life. The recognition accuracy of the two groups was compared for three musical genre: classical, country, and pop. Recognition accuracy was correlated with speech recognition scores, cognitive measures, and demographic measures, including musical background. RESULTS: Cochlear implant recipients were significantly less accurate in recognition of previously familiar (known before hearing loss) musical excerpts than normal-hearing adults (p < 0.001) for all three genre. Implant recipients were most accurate in the recognition of country items and least accurate in the recognition of classical items. There were no significant differences among implant recipients due to implant type (Nucleus, Clarion, or Ineraid), or programming strategy (SPEAK, CIS, or ACE). For cochlear implant recipients, correlations between melody recognition and other measures were moderate to weak in strength; those with statistically significant correlations included age at time of testing (negatively correlated), performance on selected speech perception tests, and the amount of focused music listening following implantation. CONCLUSIONS: Current-day cochlear implants are not effective in transmitting several key structural features (i.e., pitch, harmony, timbral blends) of music essential to open-set recognition of well-known musical selections. Consequently, implant recipients must rely on extracting those musical features most accessible through the implant, such as song lyrics or a characteristic rhythm pattern, to identify the sorts of musical selections heard in everyday life.     

Temporal Code and Speech Recognition

The hypothesis that temporal code is mainly responsible for speech recognition is discussed. Data from cochlear implant research demonstrate that single-channel speech processors, supplying only temporal code, enable understanding of spoken language. Physiological findings supporting the observation are presented. A temporal theory of tone pitch perception is discussed.     

Temporal code and speech recognition

The hypothesis that temporal code is mainly responsible for speech recognition is discussed. Data from cochlear implant research demonstrate that single-channel speech processors, supplying only temporal code, enable understanding of spoken language. Physiological findings supporting the observation are presented. A temporal theory of tone pitch perception is discussed.     

Verbal self-monitoring in deaf subjects using cochlear implants

Cortical activation during vocalization was studied in an attempt to elucidate verbal self-monitoring mechanisms in cochlear implant users. Six post-lingually deafened subjects using cochlear implants were included in this study. Significant activation was observed in the bilateral temporal cortices during reading sentences aloud, which was not found in normal subjects in our previous study. The activation patterns in the temporal cortex were similar for reading aloud and for listening to the examiner's speech, and the activation foci in the middle temporal gyri for the two tasks were almost identical. Cochlear implant users may monitor their own speech during speech production, and their verbal self-monitoring mechanisms are thought to depend on similar mechanisms that are used to monitor externally generated speech.     

Comparison of speech recognition and localization performance in bilateral and unilateral cochlear implant users matched on duration of deafness and age at implantation

OBJECTIVES: The purpose of this investigation was to compare speech recognition and localization performance of subjects who wear bilateral cochlear implants (CICI) with subjects who wear a unilateral cochlear implant (true CI-only). DESIGN: A total of 73 subjects participated in this study. Specifically, of the 73 subjects, 64 (32 CICI and 32 true CI-only) participated in the word recognition testing; 66 (33 CICI and 33 true CI-only) participated in the sentence recognition testing; and 24 (12 CICI and 12 true CI-only) participated in the localization testing. Because of time constraints not all subjects completed all testing. The average age at implantation for the CICI and true CI-only listeners who participated in the speech perception testing was 54 and 55 yrs, respectively, and the average duration of deafness was 8 yrs for both groups of listeners. The average age at implantation for the CICI and true CI-only listeners who participated in the localization testing was 54 and 53 yrs, respectively, and the average duration of deafness was 10 yrs for the CICI listeners and 11 yrs for the true CI-only listeners. All speech stimuli were presented from the front. The test setup for everyday-sound localization comprised an eight-speaker array spanning, an arc of approximately 108 degrees in the frontal horizontal plane. RESULTS: Average group results were transformed to Rationalized Arcsine Unit scores. A comparison in performance between the CICI score and the true CI-only score in quiet revealed a significant difference between the two groups with the CICI group scoring 19% higher for sentences and 24% higher for words. In addition, when both cochlear implants were used together (CICI) rather than when either cochlear implant was used alone (right CI or left CI) for the CICI listeners, results indicated a significant binaural summation effect for sentences and words. CONCLUSION: The average group results in this study showed significantly greater benefit on words and sentences in quiet and localization for listeners using two cochlear implants over those using only one cochlear implant. One explanation of this result might be that the same information from both sides are combined, which results in a better representation of the stimulus. A second explanation might be that CICI allow for the transfer of different neural information from two damaged peripheral auditory systems leading to different patterns of information summating centrally resulting in enhanced speech perception. A future study using similar methodology to the current one will have to be conducted to determine if listeners with two cochlear implants are able to perform better than listeners with one cochlear implant in noise.     

Sequential bilateral cochlear implant: results in children and adolescents

IntroductionThe use of the bilateral cochlear implants can promote the symmetrical development of the central auditory pathways, thus benefiting the development of auditory abilities and improving sound localization and the ability of auditory speech perception in situations of competitive noise.ObjectiveTo evaluate the ability of speech perception in children and adolescents using sequential bilateral cochlear implants, considering the association of these variables: age at surgery, time of device use and interval between surgeries.MethodsA total of 14 individuals between 10 and 16 years of age, who demonstrated surgical indication for the use of sequential bilateral cochlear implants as intervention in the auditory habilitation process, were assessed. The speech perception ability was assessed through sentence lists constructed in the Portuguese language, presented in two situations: in silence, with fixed intensity of 60 dB SPL, and in competitive noise, with a signal-to-noise ratio of +15 dB. The evaluation was performed under the following conditions: unilateral with the first activated cochlear implant, unilateral with the second activated cochlear implant and bilateral with both devices activated.ResultsThe results of the speech perception tests showed better performance in both silence and in noise for the bilateral cochlear implant condition when compared to the 1st cochlear implant and the 2nd cochlear implant alone. A worse result of speech perception was found using the 2nd cochlear implant alone. No statistically significant correlation was found between age at the surgical procedure, interval between surgeries and the time of use of the 2nd cochlear implant, and the auditory speech perception performance for all assessed conditions. The use of a hearing aid prior to the 2nd cochlear implant resulted in benefits for auditory speech perception with the 2nd cochlear implant, both in silence and in noise.ConclusionThe bilateral cochlear implant provided better speech perception in silence and in noise situations when compared to the unilateral cochlear implant, regardless of the interval between surgeries, age at the surgical procedure and the time of use of the 2nd cochlear implant. Speech perception with the 1st cochlear implant was significantly better than with the 2nd cochlear implant, both in silence and in noise. The use of the hearing aid prior to the 2nd cochlear implant influenced speech perception performance with the 2nd cochlear implant, both in silence and in noise.     

Music perception with temporal cues in acoustic and electric hearing

OBJECTIVE: The first specific aim of the present study is to compare the ability of normal-hearing and cochlear implant listeners to use temporal cues in three music perception tasks: tempo discrimination, rhythmic pattern identification, and melody identification. The second aim is to identify the relative contribution of temporal and spectral cues to melody recognition in acoustic and electric hearing. DESIGN: Both normal-hearing and cochlear implant listeners participated in the experiments. Tempo discrimination was measured in a two-interval forced-choice procedure in which subjects were asked to choose the faster tempo at four standard tempo conditions (60, 80, 100, and 120 beats per minute). For rhythmic pattern identification, seven different rhythmic patterns were created and subjects were asked to read and choose the musical notation displayed on the screen that corresponded to the rhythmic pattern presented. Melody identification was evaluated with two sets of 12 familiar melodies. One set contained both rhythm and melody information (rhythm condition), whereas the other set contained only melody information (no-rhythm condition). Melody stimuli were also processed to extract the slowly varying temporal envelope from 1, 2, 4, 8, 16, 32, and 64 frequency bands, to create cochlear implant simulations. Subjects listened to a melody and had to respond by choosing one of the 12 names corresponding to the melodies displayed on a computer screen. RESULTS: In tempo discrimination, the cochlear implant listeners performed similarly to the normal-hearing listeners with rate discrimination difference limens obtained at 4-6 beats per minute. In rhythmic pattern identification, the cochlear implant listeners performed 5-25 percentage points poorer than the normal-hearing listeners. The normal-hearing listeners achieved perfect scores in melody identification with and without the rhythmic cues. However, the cochlear implant listeners performed significantly poorer than the normal-hearing listeners in both rhythm and no-rhythm conditions. The simulation results from normal-hearing listeners showed a relatively high level of performance for all numbers of frequency bands in the rhythm condition but required as many as 32 bands in the no-rhythm condition. CONCLUSIONS: Cochlear-implant listeners performed normally in tempo discrimination, but significantly poorer than normal-hearing listeners in rhythmic pattern identification and melody recognition. While both temporal (rhythmic) and spectral (pitch) cues contribute to melody recognition, cochlear-implant listeners mostly relied on the rhythmic cues for melody recognition. Without the rhythmic cues, high spectral resolution with as many as 32 bands was needed for melody recognition for normal-hearing listeners. This result indicates that the present cochlear implants provide sufficient spectral cues to support speech recognition in quiet, but they are not adequate to support music perception. Increasing the number of functional channels and improved encoding of the fine structure information are necessary to improve music perception for cochlear implant listeners.     

A matched-pairs comparison of single and multichannel cochlear implants in children

Auditory capabilities of Nucleus 22 multichannel cochlear implant users were compared to those of matched 3M/House single-channel users. Six children who received either the 3M/House or Nucleus 22 cochlear implants were separated into three matched pairs. Group 1 consisted of two postlinguistically deafened adolescents, group 2 consisted of two prelinguistically deafened school-age children, and group 3 consisted of two perilinguistically deafened preschoolers. Participants were evaluated using auditory comprehension and discrimination tasks as indicated by the 3M/House and Nucleus 22 protocols. However, only tasks common to both were included here. While the 3M/House single-channel device has been under an IDE for children under the age of 18 years since 1984, the Nucleus 22 multichannel implant only recently became available for this age group. Thus, short-term evaluations at 6 months and 1 year postimplantation have been used for comparison. Two of the three groups indicated that the multichannel users performed as early as the 6-month level; the children in the third group performed equally. These results indicate that multichannel cochlear implants show great promise in deaf children.