Language and speech perception of young children with bimodal fitting or bilateral cochlear implants

Abstract

Objectives

This paper compares language development and speech perception of children with bimodal fitting (a cochlear implant in one ear and a hearing aid in the opposite ear) or bilateral cochlear implantation.

Methods

Participants were children enrolled in the Longitudinal Outcomes of Children with Hearing Impairment study. Language development was assessed at 3 years of age using standardized tests. Speech perception was evaluated at 5 years of age. Speech was presented from a frontal loudspeaker, and babble noise was presented either from the front or from both sides.

Results

On average, there was no significant difference in language outcomes between 44 children with bimodal fitting and 49 children with bilateral cochlear implants; after controlling for a range of demographic variables. Earlier age at cochlear implant activation was associated with better outcomes. Speech perception in noise was not significantly different between children with bimodal fitting and those with bilateral cochlear implants. Compared to normal-hearing children, children with cochlear implants required a better signal-to-noise ratio to perform at the same level, but demonstrated spatial release from masking of a similar magnitude.

Conclusions

This population-based study found that language scores for children with bilateral implants were higher than those with bimodal fitting or those with unilateral implants, but neither reached significance level.     

Variation in speech perception scores among children with cochlear implants

OBJECTIVE: The objective of this study was to identify common factors affecting speech perception scores in children with cochlear implants. DESIGN: Speech perception data for 167 implanted children were collected at two cochlear implant centres in Melbourne and Sydney. The data comprised audition-alone scores on open-set word and sentence tests. Children were selected on the basis that they had a Nucleus 22-electrode cochlear implant. The average age of the children was 5 yr. Information was also collected about 12 factors that may have influenced speech perception scores for each child. Analysis of covariance was used to identify factors that significantly affected speech perception scores. Pearson pairwise correlation coefficients were also calculated for all factors analyzed. RESULTS: The analyses in this study identified factors that accounted for 51%, 34%, and 45% of the variance in phoneme, word and sentence perception scores. Scores decreased by 1.4 to 2.4% per year of profound deafness prior to implantation. Children who normally use oral communication scored significantly higher than children normally using sign or simultaneous oral and sign communication. Children implanted in Sydney scored higher on average than children implanted in Melbourne. CONCLUSIONS: The results show that a significant part of the variation in speech perception scores is systematically related to audiological and environmental factors for each child. The reasons for significant differences between children using different communication modes or from different clinics were not identified.     

Comparison of bilateral and unilateral cochlear implants in children with sequential surgery

Objective

The objective of this study was to evaluate the effect of bilateral versus unilateral cochlear implants and the importance of the inter-implant interval.

Methods

Seventy-three prelingually deaf children received sequential bilateral cochlear implants. Speech recognition in quiet with the first, second and with both implants simultaneously was evaluated at the time of the second implantation and after 12 and 24 months.

Results

Mean bilateral speech recognition 12 and 24 months after the second implantation was significantly higher than that obtained with either the first or the second implant. The addition of a second implant was demonstrated to have a beneficial effect after both 12 and 24 months. Speech recognition with the second implant increased significantly during the first year. A small, non-significant improvement was observed during the second year. The inter-implant interval significantly influenced speech recognition with the second cochlear implant both at 12 and 24 months, and bilateral speech recognition at 12 months, but not at 24 months.

Conclusions

A small, but statistically significant improvement in speech recognition was found with bilateral cochlear implants compared with a unilateral implant. A major increase in speech recognition occurred with the second cochlear implant during the first year. A shorter time interval between the two implantations resulted in better speech recognition with the second implant. However, no definitive time-point was found for when the second implant could no longer add a positive effect.     

Electrode discrimination and speech perception in young children using cochlear implants

OBJECTIVE: The aim was to determine the efficacy of a child-appropriate procedure to assess electrode discrimination ability in young children using cochlear implants and to investigate the relationship of electrode discrimination ability and speech perception performance in children implanted at a young age. DESIGN: An adaptation of the play audiometry procedure was used to assess electrode discrimination in seventeen 4- to 10-yr-old children. The children were required to respond with a game-like motor response when a repeating stimulation on a reference electrode "changed" to a different electrode. They were also assessed on a speech feature discrimination test, a closed-set word recognition test and a nonverbal intelligence task. RESULTS: Sixty-five percent of subjects demonstrated ability to discriminate adjacent electrodes in mid and apical regions of the cochlea, whilst the remaining subjects needed electrode separations of between two and nine electrodes for successful discrimination. In a forward stepwise regression analysis electrode discrimination ability was found to be the strongest factor in accounting for variance in the speech perception scores. Subject variables such as duration of deafness, nonverbal intelligence and implant experience did not significantly account for further variance in the speech perception scores for this group of children. CONCLUSIONS: Electrode discrimination ability was the strongest factor in predicting performance on speech perception measures in a group of children using cochlear implants.     

Psychoacoustic performance and music and speech perception in prelingually deafened children with cochlear implants

The number of pediatric cochlear implant (CI) recipients has increased substantially over the past 10 years, and it has become more important to understand the underlying mechanisms of the variable outcomes in this population. In this study, psychoacoustic measures of spectral-ripple and Schroeder-phase discrimination, the Clinical Assessment of Music Perception, and consonant-nucleus-consonant (CNC) word recognition in quiet and spondee reception threshold (SRT) in noise tests have been presented to 11 prelingually deafened CI users, aged 8-16 years with at least 5 years of CI experience. The children's performance was compared to the previously reported results of postlingually deafened adult CI users. The average spectral-ripple threshold (n = 10) was 2.08 ripples/octave. The average Schroeder-phase discrimination was 67.3% for 50 Hz and 56.5% for 200 Hz (n = 9). The Clinical Assessment of Music Perception test showed that the average complex pitch direction discrimination was 2.98 semitones. The mean melody score was at a chance level, and the mean timbre score was 34.1% correct. The mean CNC word recognition score was 68.6%, and the mean SRT in steady noise was -8.5 dB SNR. The children's spectral-ripple resolution, CNC word recognition, and SRT in noise performances were, within statistical bounds, the same as in a population of postlingually deafened adult CI users. However, Schroeder-phase discrimination and music perception were generally poorer than in the adults. It is possible then that this poorer performance seen in the children might be partly accounted for by the delayed maturation in their temporal processing ability, and because of this, the children's performance may have been driven more by their spectral sensitivity.     

Auditory perception and speech identification in children with cochlear implants tested with the EARS protocol

The performance of children who receive a cochlear implant may be dependent on both age of the child at implantation and the amount of experience with the implant. In the present study, changes in auditory perception and speech identification were investigated with experience of 71 children who had received a cochlear implant. The children were divided into three groups, those above and those below the age of 7 years at the time of implantation, and those aged 3 years or younger deafened by meningitis. The children received either the Nucleus 22, the Nucleus 24 or the Med El C40+ implant. The test material was a reduced form of the EARS evaluation protocol developed by Med El into a multi-language format. Tests were performed pre-operatively, within 2-5 days of first fitting of the speech processor, then at 1, 3 and 6 months and every 6 months thereafter, for a total period of 24 months. The results indicated that all children showed improvement after 6-12 months. The rate of improvement differed between age groups. Children over 7 years of age had pre-operatively higher test scores than younger children, presumably because of their previous experience with hearing aids. These children showed an immediate post-operative drop in performance that recovered 1-3 months later. The children aged under 7 years started at lower performance levels but approached those of the older children after 12 months' cochlear implant use because their post-operative drop was less significant and their performance improved faster. Children who had been deafened by meningitis and implanted at the age of 3 or less made little progress over the first 6 months but approached test levels of the under-7-year-olds by 18 months or later. All three components of the evaluation protocol employed the Listening Progress Profile (LiP), the Monosyllabic-Trochee-Polysyllabic Test (MTP) and the Meaningful Auditory Integration Scale (MAIS) and proved to be valuable in demonstrating improvement in performance of cochlear implant children in all age groups once the immediate post-operative drop had been overcome.     

Amplitude-mapping effects on speech intelligibility with unilateral and bilateral cochlear implants

OBJECTIVE: A study was conducted examining the effects of amplitude-mapping adjustments on speech intelligibility with bilateral cochlear implant users, for both unilateral and bilateral device use. The main motivation for this study was the consideration that bilateral loudness summation may result in sounds becoming too loud if no adjustments are made to standard monaural amplitude-mapping functions (maps) when used bilaterally. In that case, reductions of the stimulation levels may be needed. The objective was to assess the impact of such adjustments on speech intelligibility in noise and in quiet. DESIGN: Four different maps were compared in eight bilateral users of the Nucleus 24 system. Each map variation was taken home for 1 week and used bilaterally. After each week, the map used was tested both unilaterally and bilaterally using an adaptive speech-in-noise test and bilaterally for low-level speech in quiet. For the tests in noise, both speech and noise were presented from the same loudspeaker placed directly in front of the listener (S0N0). One of the maps evaluated was a standard clinical map, fitted as if only one ear were to be used. The three other maps used stimulation levels that were reduced more near the maximal stimulation levels, near thresholds, or else by a similar amount over the entire dynamic range. RESULTS: The data showed a modest but statistically significant decrease in performance when stimulation levels were lowered. This was true both in noise and in quiet. For level reductions corresponding to binaural loudness summation effects, the performance decrease was on the order of 1 to 2 dB. Altering the slope of the map had relatively little effect on performance. Comparison of unilateral with bilateral performance using the same map (i.e., no compensation for bilateral loudness summation) and with speech and noise both presented from in front of the listeners showed a modest but statistically significant improvement in the bilateral condition. CONCLUSIONS: Using higher stimulation levels in amplitude-mapping functions can improve both monaural and binaural speech perception performance in quiet and in noise, even when the slope of the acoustic to electrical amplitude-mapping function is held constant (i.e., when the electrical signal-to-noise ratio remains constant). The results in noise can be understood if we assume that the relation between electrical stimulation levels and loudness grows faster at higher stimulation levels. When comparing the monaural better ear with binaural performance in noise (S0N0) by using the same map, that is to say, when no adjustments were made in the bilateral condition for bilateral loudness summation, an average signal-to-noise ratio benefit of 1.4 dB was found in the bilateral condition. These findings indicate that when fitting bilateral devices clinically, although binaural performance may decrease slightly if levels need to be reduced to compensate for binaural loudness summation, the binaural S0N0 advantage over the better ear will offset this. Consequently, performance with both ears after adjustment is likely to remain at least as good as for the better ear alone without level adjustment, even in the S0N0 condition where binaural advantages are minimized.     

Perceptual benefit and functional outcomes for children using sequential bilateral cochlear implants

OBJECTIVE: To evaluate the additional perceptual benefit provided to children through the use of two cochlear implants in comparison to one after 6 to 13 mo experience with sequential bilateral implants. DESIGN: A second cochlear implant was received by 11 children. The principal selection criteria were being age 4 to 15 yr with a bilateral profound hearing loss and being a consistent user of a first implant with a commitment to use of a second implant. Horizontal localization was assessed by using pink noise bursts presented from a 180 degrees , eight-loudspeaker array. Speech perception was assessed by using a four-alternative forced-choice spondee test, with speech presented from in front and adaptive background noise presented from 90 degrees to the left or right. Both tests were completed in the first implant alone and bilateral conditions. A questionnaire measured the pre- to postoperative change in the parent's ratings of the child's performance in specific listening situations. Items were related to speech perception, spatial hearing, or other qualities of hearing. Regular parental reports of device use, attitude and performance were collected. Most subjects were assessed at 6 mo after surgery, with two assessed at 13 mo. RESULTS: The 11 subjects demonstrated a great range of outcomes. For one subject, only anecdotal data were collected. Speech perception testing indicated that when noise was presented ipsilateral to the first implant, 8 of 10 subjects showed a benefit in the bilateral condition. None of the nine subjects tested showed a benefit when noise was contralateral to the first implant. Generally, there was no benefit to localization in the bilateral condition. For eight subjects, postoperative performance ratings were generally higher than preoperative ratings, particularly in the spatial hearing section. Anecdotal reports indicated that most subjects had a negative attitude toward, and gained limited experience with, the second implant alone. The subjects developed a range of speech perception skills, from detection to conversation level. Regarding the use of bilateral implants, attitudes were more positive and device use was consistent for eight subjects, and six parents reported some evidence of improved performance in daily life. CONCLUSIONS: Children over age 4 yr may gain significant additional benefit from a second implant, including improved speech perception in some noise contexts and functional advantages in daily life. There is, however, no evidence from this study to suggest that binaural listening skills, including localization, will develop during the first 6 mo. Furthermore, some children who may be committed users of a first implant may not adapt to or benefit from a second implant during the first 6 mo of device use. Although the factors influencing benefit cannot be clearly identified, limited preoperative auditory experience with the second ear, a delay of years between implants, relatively advanced age, and lack of second-implant-alone experience do not preclude benefit. Continued evaluation of these and additional subjects will clarify the factors that do contribute to benefit. Such information will be vital in helping families of implanted children to make an informed decision regarding a second implant.     

双侧人工耳蜗植入术后言语识别效果的评估

目的评估双侧人工耳蜗植入者汉语普通话短句、双音节词单音节词及汉语声调的识别效果,探索双侧人工耳蜗植入者双耳听觉产生的机制及对言语识别率的影响。方法选取双侧人工耳蜗植入患者6人,自制问卷收集受试者的基本信息并评估他们的主观听觉状况。首先测试受试者在使用双侧人工耳蜗（BCI）、单独使用一侧人工耳蜗（RCI/LCI）的听阈,随后测试他们在BCI和RCI/LCI两种听觉模式下的七音节短句、双音节词、声调、韵母、声母识别率,测试背景环境包括安静环境和嘈杂语噪声环境,言语信号强度为65dB SPL,固定信噪比为+10 dB SPL。随后将BCI和RCI/LCI两种听觉模式下的识别效果进行比较。结果除噪声状态下韵母识别测试中其余测试结果均为BCI言语识别率得分高于RCI/LCI。结论对于符合双侧人工耳蜗植入术适应证标准的患者而言,双侧植入人工耳蜗可以在不同程度上提高安静和噪声环境下的短句、双字词、声母、韵母及声调的识别率,降低其声场听阈。     

Neuroelectrical imaging study of music perception by children with unilateral and bilateral cochlear implants

Abstract

Objective

To investigate by means of non-invasive neuroelectrical imaging the differences in the perceived pleasantness of music between children with cochlear implants (CI) and normal-hearing (NH) children.

Methods

5 NH children and 5 children who received a sequential bilateral CI were assessed by means of High-Resolution EEG with Source Reconstruction as they watched a musical cartoon. Implanted children were tested before and after the second implant. For each subject the scalp Power Spectral Density was calculated in order to investigate the EEG alpha asymmetry.

Results

The scalp topographic distribution of the EEG power spectrum in the alpha band was different in children using one CI as compared to NH children (see figure). With two CIs the cortical activation pattern changed significantly, becoming more similar to the one observed in NH children.

Conclusions

The findings support the hypothesis that bilateral CI users have a closer-to-normal perception of the pleasantness of music than unilaterally implanted children.     

The effect of pre-operative developmental delays on the speech perception of children with cochlear implants

Objective

The objective of this study was to evaluate the relationship between developmental delays and speech perception in pre-lingually deafened cochlear implant recipients.

Methods

This study was a retrospective review of patient charts conducted at a tertiary referral center. Thirty-five pre-lingually deafened children underwent multichannel cochlear implantation and habilitation at the Kyoto University Hospital Department of Otolaryngology-Head and Neck Surgery. A pre-operative cognitive–adaptive developmental quotient was evaluated using the Kyoto scale of psychological development. Post-operative speech performance was evaluated with speech perception tests two years after cochlear implantation. We computed partial correlation coefficients (controlled for age at the time of implantation and the average pre-operative aided hearing level) between the cognitive–adaptive developmental quotient and speech performance.

Results

A developmental delay in the cognitive–adaptive area was weakly correlated with speech perception (partial correlation coefficients for consonant–vowel syllables and phrases were 0.38 and 0.36, respectively).

Conclusion

A pre-operative developmental delay was only weakly associated with poor post-operative speech perception in pre-lingually deafened cochlear implant recipients.     

Rate-of-processing ability in children using cochlear implants and its relevance to speech perception

The aim was to assess the ability of young children using cochlear implants to process a change in place of stimulation under conditions of shortened stimulus duration and shortened interstimulus interval. The study investigated whether or not this ability accounted for a significant amount of the variance in the speech performance of the children additional to the variance accounted for by electrode discrimination ability (measured in a previous study). An adaptation of the play audiometry procedure was used to assess 'rate-of-processing' ability in 17 children aged between 4 and 10 years. Initially the child was required to respond with a game-like motor response when a repeating stimulation on a reference electrode 'changed' to a different electrode in relatively 'slow' conditions. The child was then required to respond to the 'change', when the duration of the stimuli and the time interval between the stimuli were decreased. All but one of the children using cochlear implants scored significantly above chance for all conditions of stimulus duration and interstimulus interval assessed. That is, they were able to discriminate place pitch changes when these changes occurred more rapidly in time. A stepwise regression was computed to determine the relative contributions of a number of variables, including rate-of-processing ability, in accounting for variance in the children's speech perception performance (measured in a previous study). Rate-of-processing ability did not account for any variance additional to that accounted for by electrode discrimination ability, which was found to be the most significant predictor of speech perception performance for this group of children in the previous study.     

Rate-of-processing ability in children using cochlear implants and its relevance to speech perception

Abstract

The aim was to assess the ability of young children using cochlear implants to process a change in place of stimulation under conditions of shortened stimulus duration and shortened interstimulus interval. The study investigated whether or not this ability accounted for a significant amount of the variance in the speech performance of the children additional to the variance accounted for by electrode discrimination ability (measured in a previous study). An adaptation of the play audiometry procedure was used to assess ‘rate-of-processing’ ability in 17 children aged between 4 and 10 years. Initially the child was required to respond with a gamelike motor response when a repeating stimulation on a reference electrode ‘changed’ to a different electrode in relatively ‘slow’ conditions. The child was then required to respond to the ‘change’, when the duration of the stimuli and the time interval between the stimuli were decreased. All but one of the children using cochlear implants scored significantly above chance for all conditions of stimulus duration and interstimulus interval assessed. That is, they were able to discriminate place pitch changes when these changes occurred more rapidly in time. A stepwise regression was computed to determine the relative contributions of a number of variables, including rate-of-processing ability, in accounting for variance in the children's speech perception performance (measured in a previous study). Rate-of-processing ability did not account for any variance additional to that accounted for by electrode discrimination ability, which was found to be the most significant predictor of speech perception performance for this group of children in the previous study.     

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.     

Electrical stimulation rate effects on speech perception in cochlear implants

The objective of this study was to explore cochlear implant users’ speech perception performance in quiet and in noise for low to moderate stimulation rates. Eight postlingually deaf adult users of the Nucleus CI24 cochlear implant (contour electrode array) using the ESPrit 3G speech processor participated in this study. Monosyllabic word recognition in quiet and sentence perception in noise was evaluated for low to moderate stimulation rates of 275, 350, 500, and 900 pulses-per-second/channel (pps/ch). All four stimulation rate programs were balanced for loudness. A repeated ABCD experimental design was employed. Take home practice was provided with each stimulation rate. Subjects also responded to a comparative questionnaire to examine their rate preference for a variety of listening situations. Results for six of the eight subjects showed no significant effect of rate for monosyllables in quiet. However, results for the sentence test in noise demonstrated improvements with 500 or 900 pps/ch stimulation rates in seven out of the eight subjects. Although there was not a close relationship between each subject's subjective preference and the rate program that provided best speech perception, most subjects indicated a preference for 500 pps/ch rate in noise.