Results using the OPAL strategy in Mandarin speaking cochlear implant recipients

Abstract

Objective: To evaluate the effectiveness of an experimental pitch-coding strategy for improving recognition of Mandarin lexical tone in cochlear implant (CI) recipients. Design: Adult CI recipients were tested on recognition of Mandarin tones in quiet and speech-shaped noise at a signal-to-noise ratio of?+10?dB; Mandarin sentence speech-reception threshold (SRT) in speech-shaped noise; and pitch discrimination of synthetic complex-harmonic tones in quiet. Two versions of the experimental strategy were examined: (OPAL) linear (1:1) mapping of fundamental frequency (F0) to the coded modulation rate; and (OPAL+) transposed mapping of high F0s to a lower coded rate. Outcomes were compared to results using the clinical ACE? strategy. Study sample: Five Mandarin speaking users of Nucleus® cochlear implants. Results: A small but significant benefit in recognition of lexical tones was observed using OPAL compared to ACE in noise, but not in quiet, and not for OPAL+?compared to ACE or OPAL in quiet or noise. Sentence SRTs were significantly better using OPAL+?and comparable using OPAL to those using ACE. No differences in pitch discrimination thresholds were observed across strategies. Conclusions: OPAL can provide benefits to Mandarin lexical tone recognition in moderately noisy conditions and preserve perception of Mandarin sentences in challenging noise conditions.     

Tone perception in Mandarin-speaking children with cochlear implants

Abstract

Objective: To evaluate the effects of implant age and duration of implantation on development of Mandarin tone perception in paediatric cochlear implant recipients. Design: Retrospective cross-sectional evaluation of tone perception, as assessed with the Mandarin Early Speech Perception test at 3, 6, 12, 24, 36 and 48 months after activation. Study sample: A total of 143 subjects, 60 girls and 83 boys unilaterally implanted at 1–4 years of age comprised the sample. All the subjects were implanted with devices from one of three manufacturers. Results: Regardless of implant age, approximately 80% of the subjects obtained overall tone discrimination scores significantly above chance by 4 years after implantation, and average discrimination accuracy increased from approximately 68% to 79%. Acoustically distinct tones 1 and 4 were discriminated and recognised more accurately, while less distinct tones 2 and 3 were discriminated and recognised less accurately. Large individual differences in performance were evident. Conclusions: Most Mandarin-speaking paediatric CI recipients discriminate tones above chance at 5 years of age with accuracy comparable to that of children with normal hearing at 2 years of age. Modest benefits of early implantation are evident.     

Bimodal benefits in Mandarin-speaking cochlear implant users with contralateral residual acoustic hearing

Abstract

Objective: The present study aimed to measure bimodal benefits and probe their underlying mechanisms in Mandarin-speaking cochlear implant (CI) subjects who had contralateral residual acoustic hearing. Design: The subjects recognised words or phonemes from the Mandarin Lexical Neighborhood Test in noise at a 10-dB signal-to-noise ratio (SNR) with acoustic stimulation, electric stimulation or the combined bimodal stimulation. Study sample: Thirteen Mandarin-speaking subjects wore a CI in one ear and had residual acoustic hearing in the contralateral ear. Six of the subjects (5.2–13.0 years) had pre-lingual onset of severe hearing loss, and seven of them (8.6–45.8 years) had post-lingual onset of severe hearing loss. Results: Both groups of subjects produced a significant bimodal benefit in word recognition in noise. Consonants and tones accounted for the bimodal benefit. The bimodal integration efficiency was negatively correlated with the duration of deafness in the implanted ear for vowel recognition but positively correlated with CI or bimodal experience for consonant recognition. Conclusions: The present results support preservation of residual acoustic hearing, early cochlear implantation and continuous use of bimodal hearing for subjects who have significant residual hearing in the non-implanted ear.     

Speech recognition with a cochlear implant using triphasic charge-balanced pulses

Objective Typically, symmetrical charge-balanced biphasic current pulses are used in cochlear implants to ensure biological safety. Theoretically, monophasic pulses are more effective, but potentially noxious, stimuli. In this study we charge-balanced such monophasic pulses during selected non-stimulated intervals, effectively leading to triphasic pulses with a 4:1 amplitude ratio between the cathodic and anodic phases. Apart from ensuring safety, this is also expected to reduce power consumption and channel interaction.

Material and Methods Seven experienced Clarion CII cochlear implant users with a multichannel (12–16 channels) monopolar continuous interleaved sampling (CIS) strategy participated in the study. Three different CIS strategies were fitted using the Clarion Research Interface (CRI-2). The reference was an implementation of each subject's own CIS program. The two strategies tested used triphasic pulses on the same channels, one with half-wave rectification (TP-HWR) and one without rectification (TP-NoR) at the input. Directly after fitting (i.e. without any training), speech perception (phoneme score on consonant–vowel–consonant words) was measured in silence (sound-only) and in speech-shaped background noise with signal:noise ratios (SNRs) of +5 and 0 dB.

Results Speech perception with the reference via the CRI-2 was equal to that of the free-field condition with the subjects’ own speech processor. With the TP-NoR strategy, speech perception improved significantly (from 89% to 93%) in silence and in the 0-dB SNR condition (from 43% to 49%). With a SNR of +5 dB, performance was stable at ≈66%. With the TP-HWR strategy, performance increased significantly in the 0- and +5-dB SNR conditions, to 55% and 74%, respectively. Power consumption was reduced in both strategies, to 30% and 36% for TP-HWR and TP-NoR, respectively.

Conclusion The new triphasic strategies are most promising, with respect to both their improved speech perception and reduced power requirements. The optimal parameters will have to be identified following long-term use.     

Mandarin Chinese speech recognition by pediatric cochlear implant users

Objectives

Because of difficulties associated with pediatric speech testing, most pediatric cochlear implant (CI) speech studies necessarily involve basic and simple perceptual tasks. There are relatively few studies regarding Mandarin-speaking pediatric CI users’ perception of more difficult speech materials (e.g., words and sentences produced by multiple talkers). Difficult speech materials and tests necessarily require older pediatric CI users, who may have different etiologies of hearing loss, duration of deafness, CI experience. The present study investigated how pediatric CI patient demographics influence speech recognition performance with relatively difficult test materials and methods.

Methods

In this study, open-set recognition of multi-talker (two males and two females) Mandarin Chinese disyllables and sentences were measured in 37 Mandarin-speaking pediatric CI users. Subjects were grouped according to etiology of deafness and previous acoustic hearing experience. Group 1 subjects were all congenitally deafened with little-to-no acoustic hearing experience. Group 2 subjects were not congenitally deafened and had substantial acoustic hearing experience prior to implantation. Multiple linear regression analyses were performed within each group using subject demographics such as age at implantation and age at testing.

Results

Pediatric CI performance was generally quite good. For Group 1, mean performance was 82.3% correct for disyllables and 82.8% correct for sentences. For Group 2, mean performance was 76.6% correct for disyllables and 84.4% correct for sentences. For Group 1, multiple linear regression analyses showed that age at implantation predicted disyllable recognition, and that age at implantation and age at testing predicted sentence recognition. For Group 2, neither age at implantation nor age at testing predicted disyllable or sentence recognition. Performance was significantly better with the female than with the male talkers.

Conclusions

Consistent with previous studies’ findings, early implantation provided a significant advantage for profoundly deaf children. Performance for both groups was generally quite good for the relatively difficult materials and tasks, suggesting that open-set word and sentence recognition may be useful in evaluating speech performance with older pediatric CI users. Differences in disyllable recognition between Groups 1 and 2 may reflect differences in adaptation to electric stimulation. The Group 1 subjects developed speech patterns exclusively via electric stimulation, while the Group 2 subjects adapted to electric stimulation relative to previous acoustic patterns.     

汉语普通话人工耳蜗使用者对声调识别的分析研究

目的 初步确定人工耳蜗使用者声调感知的特点,并进行分析研究.方法 利用自主开发的噪声下声调识别测试材料(tone identification in noise test,TINT)在Speech Performance测试平台的控制下对20例母语为汉语普通话人工耳蜗使用者声调识别能力进行评估,获得各声调识别成绩以及声调识别混淆矩阵.采用χ2检验(chi-square test)对本组人工耳蜗使用者汉语声调识别成绩差异进行统计学分析.结果 ①本组人工耳蜗使用者的汉语普通话声调识别总成绩(百分制得分)分布48.75%~98.75%,平均成绩(76.38±17.29)%;②各声识别成绩平均值差异显著(χ2=2358.357,P<0.01),由高到低分别为T3(85.75%)>T4(85.25%)>T1(69.75%)>T2(64.75%),即本组人工耳蜗植入者感知T3、T4较为容易、感知T1、T2较为困难;③声调识别混淆矩阵提示T2(35.35%)、T1(30.25%)混淆度明显高于T4(14.75%)、T3(14.25%),并且各个声调之间的混淆趋势不同,T1易被混淆为T2(18.25%)、T2易被混淆为T3(24.00%).结论 时域特性明显的声调更易被人工耳蜗群体识别,因此应根据声调感知难易程度制定针对性的声调康复训练方案,综合利用听觉信息和视觉信息改善声调,特别是一声、二声的识别能力.     

Speech and music perception with the new fine structure speech coding strategy: preliminary results

Conclusions. Taking into account the excellent results with significant improvements in the speech tests and the very high satisfaction of the patients using the new strategy, this first implementation of a fine structure strategy could offer a new quality of hearing with cochlear implants (CIs). Objective. This study consisted of an intra-individual comparison of speech recognition, music perception and patient preference when subjects used two different speech coding strategies with a MedEl Pulsar CI: continuous interleaved sampling (CIS) and the new fine structure processing (FSP) strategy. In contrast to envelope-based strategies, the FSP strategy also delivers subtle pitch and timing differences of sound to the user and is thereby supposed to enhance speech perception in noise and increase the quality of music perception. Patients and methods. This was a prospective study assessing performance with two different speech coding strategies. The setting was a CI programme at an academic tertiary referral centre. Fourteen post-lingually deaf patients using a MedEl Pulsar CI with a mean CI experience of 0.98 years were supplied with the new FSP speech coding strategy. Subjects consecutively used the two different speech coding strategies. Speech and music tests were performed with the previously fitted CIS strategy, immediately after fitting with the new FSP strategy and 4, 8 and 12 weeks later. The main outcome measures were individual performance and subjective assessment of two different speech processors. Results. Speech and music test scores improved statistically significantly after conversion from CIS to FSP strategy. Twelve of 14 patients preferred the new FSP speech processing strategy over the CIS strategy.     

Effects of limiting the number of active electrodes on mandarin tone perception in young children using cochlear implants

Objective—To evaluate the short-term effects of varying the number and location of programmed electrodes on Mandarin tone perception in young children using Nucleus CI 24 implants.

Material and Methods—Six children using CI 24 implants participated in the study. The Mandarin tone recognition of each subject was assessed using a self-designed word list containing 80 words under 5 different map conditions. The map conditions were: (i) the subject's current map with all functional electrodes; (ii) removing (i.e. not programming) the even-numbered active electrodes; (iii) removing the five most apical electrodes; (iv) removing the six most basal electrodes; and (v) removing all electrodes except the six most apical.

Results—Reducing the number of active electrodes caused a small but significant decrease in performance of Mandarin tone perception. However, a relatively high tone perception score (58.1%) could be maintained even when subjects used only six apical electrodes. The location of the electrodes, i.e. apical or basal, did not appear to be important in tone perception. For each individual tone, the scores for tones 1 and 4 were significantly higher than those for tones 2 and 3 for all map conditions. Comparing tone perception with word recognition, reducing the number of active electrodes had a much more negative effect on word recognition.

Conclusions—A small but significant decrease in Mandarin tone perception was observed when the number of active electrodes was reduced in children using CI 24 implants. The location of the electrode is not important in tone recognition. Moreover, tone recognition is far more resistant than word recognition to the negative effects of reducing the number of active programmable electrodes, possibly because it relies mostly on temporal envelopes while word recognition requires more spectral details.     

诺尔康人工耳蜗植人者的声调识别与生活质量评价

目的：评估诺尔康人工耳蜗植入者对普通话的声调识别能力和术后生活质量。方法：49例植入诺尔康人工耳蜗1年的受试者,使用课题组前期编制的声调识别测试软件,评估植入者的声调识别能力;使用Ni-jmegen人工耳蜗植入量表（NCIQ）,评估植人者术后生活质量。结果：①安静条件下声调识别率平均为67．26％,全部高于机会水平;②噪声条件下声调识别率平均为51．92％,除2例植入者的声调识别率低于机会水平外,其余均高于机会水平;③声调识别混淆矩阵结果显示,三声为较容易辨别的声调;④术后NCIQ总分及基本声音感知、高级声音感知、言语能力、自信心、活动能力和交流能力均获得改善,分别为55．4、72．4、54．0、63．4、50．7、47．3和44．7分。结论：诺尔康人工耳蜗植入者术后具有声调识别能力并可获得生活质量的改善。     

Speech perception in Mandarin-speaking children with cochlear implants: A systematic review

Abstract

Objective: This paper reviewed the literature on the trajectories and the factors significantly affecting post-implantation speech perception development in Mandarin-speaking children with cochlear implants (CIs). Design: A systematic literature search of textbooks and peer-reviewed published journal articles in online bibliographic databases was conducted. Study sample: PubMed, Scopus and Wiley online library were searched for eligible studies based on predefined inclusion and exclusion criteria. Results: A total of 14 journal articles were selected for this review. A number of consistent results were found. That is, children with CIs, as a group, exhibited steep improvement in early speech perception, from exhibiting few prelingual auditory behaviours before implantation to identifying sentences in noise after one year of CI use. After one to three years of CI use, children are expected to identify tones above chance and recognition of words in noise. In addition, early age at implantation, longer duration of CI use and higher maternal education level contributed to greater improvements in speech perception. Conclusions: Findings from this review will contribute to the establishment of appropriate short-term developmental goals for Mandarin-speaking children with CIs in mainland China and clinicians could use them to determine whether children have made appropriate progress with CIs.     

Lexical tone identification and consonant recognition in acoustic simulations of cochlear implants

Conclusion: Cochlear implant (CI) recipients’ performance of lexical tone identification and consonant recognition can be enhanced by providing greater spectral details. Objective: To evaluate the effects of increasing the number of total spectral channels on the lexical tone identification and consonant recognition by normally hearing listeners who are native speakers of Mandarin Chinese. Subjects and methods: Lexical tone identification and consonant recognition were measured in 15 Mandarin-speaking, normal-hearing (NH) listeners with varied numbers of total spectral channels (i.e. 4, 6, 8, 10, 12, 16, 20, and 24), using acoustic simulations of CIs. Results: The group of NH listeners’ performance of lexical tone identification ranged from 44.53% to 66.60% with 4–24 spectral channels. The performance of tone identification between channels 4 and 16 remained similar; between channels 16 and 20 performance improved significantly. As regards consonant recognition, the NH listeners’ overall accuracy ranged from 73.17% to 95.33% with 4–24 channels. Steady improvement in consonant recognition accuracy was observed as a function of increasing the spectral channels. With about 12–16 spectral channels, the NH listeners’ overall accuracy in consonant recognition began to be comparable to their accuracy with the unprocessed stimuli.     

低年龄段语前聋儿童人工耳蜗植入后汉语声调识别变化的分析

目的:探讨低年龄段经人工耳蜗植入的语前聋儿童经过开机一段时间后声调识别的变化特点。方法:选择29例已经接受人工耳蜗植入的低年龄语前聋儿童,按植入时年龄分为2组,即A组:3.0~4.5岁,B组:5.0~6.5岁,植入后平均开机时间为1.5~2.0年。采用聋康系统的《聋儿听觉言语康复评估词表》中主要反映声调识别的相应评估内容进行封闭项测试。结果:A组:同音单音节声调识别率为(63.00±16.75)%,双音节声调识别率为(75.60±11.18)%,单音节词识别率为(72.38±11.39)%。B组:同音单音节声调识别率为(49.46±13.91)%,双音节声调识别为(64.71±9.64)%,单音节词识别率为(55.71±8.59)%。所有正确识别率结果均大于机会水平。人工耳蜗植入后不同年龄组患儿有关声调识别的三项测试内容,低年龄组患儿均好于高年龄组,结果均差异有统计学意义。结论:对于语前聋行人工耳蜗植入的低年龄儿童,植入时年龄仍是影响植入后声调识别的重要因素之一,而在更能反映汉语声、韵、调特点的单音节词中差异更为明显,因此植入年龄是术后汉语学习的重要影响因素之一。     

Tone production and perception and intelligibility of produced speech in Mandarin-speaking cochlear implanted children

Objective: This study explored tone production, tone perception and intelligibility of produced speech in Mandarin-speaking prelingually deaf children with at least 5 years of cochlear implant (CI) experience. Another focus was on the predictive value of tone perception and tone production as they relate to speech intelligibility. Design: Cross-sectional research. Study sample: Thirty-three prelingually deafened children aged over eight years with over five years of experience with CI underwent tests for tone perception, tone production, and the Speech Intelligibility Rating (SIR). A Pearson correlation and a stepwise regression analysis were used to estimate the correlations among tone perception, tone production, and SIR scores. Results: The mean scores for tone perception, tone production, and SIR were 76.88%, 90.08%, and 4.08, respectively. Moderately positive Pearson correlations were found between tone perception and production, tone production and SIR, and tone perception and SIR (p?p?p?p?Conclusions: Mandarin-speaking cochlear-implanted children with sufficient duration of CI use produce intelligent speech. Speech intelligibility can be predicted by tone production performance.     

Effect of spatial separation and noise type on sentence recognition by Mandarin-speaking cochlear implant users

Objectives: To investigate the effects of spatial separation and noise type on sentence recognition by unilateral Mandarin-speaking cochlear implant (CI) users and normal-hearing (NH) listeners.

Method: Twenty-two unilateral Mandarin-speaking CI users and six NH listeners participated in this study. Speech reception thresholds were measured for three noise types (steady state noise, speech babble, and music). Sentences from the Mandarin Speech Perception test were presented directly in front of the listener (0°). Noise was presented from one of the five speaker locations: ?90°, ?45°, 0°,?+45°, and?+90°.

Results: Overall, CI performance was significantly poorer than NH performance for all spatial separation and noise type conditions. NH listeners performed best with music and poorest with steady noise. CI users performed best with steady noise, and poorest with babble. Performance was significantly affected by noise location and noise type. There was no significant difference in head shadow effects among the different noise types for CI users.

Conclusions: Performance was much poorer in CI than in NH listeners for all noise types and spatial separations. Noise type differently affected unilateral CI users and NH listeners. The limited spectral resolution in CI users did not appear to affect head shadow.     

Open-set speech perception in adult cochlear implant users with ossified cochleae

Abstract

This study describes open-set speech recognition in cochlear implant subjects with ossified cochleae and compares it to a control group with open cochleae. Twenty-one postlingually deafened adults with a Med-El Combi 40/40+GB splitelectrode implant were matched to patients using a Med-El cochlear implant with a standard electrode. Speech recognition was assessed over an 18-month period. Splitelectrode patients improved significantly over time, but their scores were significantly lower and increased significantly slower than those of controls. Of 14 patients with a duration of deafness less than 20 years, average sentence test scores were 50%, and average monosyllabic word test scores were 31%. This study provides evidence that cochlear implantation is beneficial to patients with ossified cochleae, but early implantation is advisable.     

Assessing speech recognition abilities with digits in noise in cochlear implant and hearing aid users

Objective: The primary objective of the study was to investigate the feasibility, reliability, and validity of the Dutch digits in noise (DIN) test for measuring speech recognition in hearing aid and cochlear implant users and compare results to the standard sentences-in-noise (SIN) test. Design: The relation between speech reception thresholds for DIN test and SIN test was analysed to determine the validity of the DIN test. As linguistic skills were expected to make different contributions in these tests, their influence was analysed. Study sample: Participants were 12 normal-hearing listeners, 24 hearing aid users, and 24 cochlear implant users. Results: The DIN test was feasible for more participants than the SIN test. Intraclass correlation coefficients showed high reliability. The standard error of measurement was smaller for the DIN test than for the SIN test. DIN test and SIN test were highly correlated (r = 0.95 and r = 0.56 for NH+ HA and CI users respectively). In the regression analysis no significant contribution of basic linguistic skills or personal factors was found. Conclusion: In the assessment of speech recognition in noise of aided hearing-impaired listeners with hearing aids or cochlear implants, the DIN test is a feasible, reliable and valid test.     

Non-auditory stimulation in adult cochlear implant users

Abstract

This is a retrospective case review of all 163 adults to have received multichannel cochlear implants on the Manchester University/Manchester Royal Infirmary programme between 1988 and 1998. The aims were to investigate the incidence of unwanted non-auditory effects of electrical stimulation (NAS) of the cochlea, and to try to identify any factors that seemed to be related to these effects. The effectiveness of programming strategies in eliminating unwanted effects was also studied. Most of the devices were Nucleus CI 22M or CI 24M. The remainder were Med-el Combi 40 or Combi 40+. NAS occurred in 23.9% of implantees. There were 20 cases of facial nerve stimulation (12.3%), 18 cases of pain in the ear or throat (11.0%) and one case of vestibulospinal spinal stimulation (0.6%). Two aetiologies were significantly associated with NAS. Otosclerosis tended to be associated with facial nerve stimulation and skull base fracture was associated with pain. Pain was associated with electrodes stimulated in the base turn of the cochlea and facial nerve stimulation tended to occur with more distally situated electrodes, close to labyrinthine segment of the nerve. There was no association with one particular make of device. The T and C levels for the rogue electrodes were in the normal range. It is concluded that the unwanted effects result from shorting of current through areas of low electrical resistance in the temporal bone. A number of different strategies were employed to prevent the effect, including alteration of current levels, removal of electrodes from the map and changing the stimulation mode, and this was successfully achieved in all cases. There was no difference between the performance of patients who had had NAS and those who had not, as assessed on open-set BKB sentence scores.