Relationships between speech production and speech perception skills in young cochlear-implant users

The Auditory Perception of Consonant Contrasts in Cochlear Implant Children

Background and ObjectivesA major part of speech perception is based on understanding and distinguishing between vocal cues in the speaker's speech. Consonants and vowels are vocal cues that can be affected by hearing impairment and their perception may thus be reduced or distorted. The present study aims to investigate the auditory perception of consonant contrasts in cochlear implant children. Materials and Methods The present cross-sectional, descriptive-analytical study was conducted on 24 cochlear implant children aged 9-13 selected through convenience sampling from schools and cochlear implant centers. A test of non-word pairs based on a study conducted by Khavar-Ghazlani was carried out to measure contrast in consonants, place of and manner of articulation and voicing. Results The results of the test showed that cochlear implant children scored lower in the perception of voicing compared to the other two features. No significant differences were observed between their perceptions of place of articulation and manner of articulation. Conclusion Cochlear implant children appear to have a poorer perception of voicing contrast compared to the other features, which may be due to the greater reliance of this feature on auditory signs.

The Acquisition of Acoustic Cues to Onset and Coda Voicing Contrasts by Preschoolers With Hearing Loss

PURPOSE

Children with hearing loss (HL), including those with hearing aids (HAs) and cochlear implants (CIs), often have difficulties contrasting words like " b each" versus " p each" and "do g " versus "do ck " due to challenges producing systematic voicing contrasts. Even when acoustic contrasts are present, these may not be perceived as such by others. This can cause miscommunication, leading to poor self-esteem and social isolation. Acoustic evidence is therefore needed to determine if these children have established distinct voicing categories before entering school and if misperceptions are due to a lack of phonological representations or due to a still-maturing implementation system. The findings should help inform more effective early intervention.

METHOD

Participants included 14 children with HL (eight HA users, five CI users, and one bimodal) and 20 with normal hearing, all English-speaking preschoolers. In an elicited imitation task, they produced consonant-vowel-consonant minimal pair words that contrasted voicing in word-initial (onset) or word-final (coda) position at all three places of articulation (PoAs).

RESULTS

Overall, children with HL showed acoustically distinct voicing categories for both onsets and codas at all three PoAs. Contrasts were less systematic for codas than for onsets, as also confirmed by adults' perceptual ratings.

CONCLUSIONS

Preschoolers with HL produce acoustic differences for voiced versus voiceless onsets and codas, indicating distinct phonological representations for both. Nonetheless, codas were less accurately perceived by adult raters, especially when produced by CI users. This suggests a protracted development of the phonetic implementation of codas, where CI users, in particular, may benefit from targeted intervention.

Development of fricative production in French-speaking school-aged children using cochlear implants and children with normal hearing

In the course of productive phonological development, fricatives are among the last speech sounds to emerge and to be mastered by children, probably because of the high degree of articulatory precision they require or because of difficulties with their perception. Children with cochlear implants (CI) face additional difficulties with fricative perception, since high spectral frequency components are shown to be especially difficult to perceive with a cochlear implant. Studying fricative production in children with CIs allows to study how the partial transmission of speech sounds by cochlear implants influences children's speech production, and therefore to explore how perceptual abilities influence the late stages of phonological development. This acoustic study focuses on fricative production at three places of articulation (i.e., /f/, /s/ and /ʃ/), comparing productions by two groups of children (20 children with normal hearing (NH) vs. 13 children with CIs, all aged 5;7 to 10;7 years), and taking into account their consistency in coarticulation and the stability of their production across two different tasks (word-repetition and picture-naming). Statistical analyses were carried out by means of linear mixed-effect models. The results show that while both groups produce /ʃ/ with similar acoustic characteristics, between-group differences are found for /f/ and /s/. Furthermore, effects of consonant-vowel coarticulation are found for children with NH, and are absent for children with CIs. Effects of chronological age are only found for children with CIs (production in older children with CIs nearing that of children with NH). Our study shows that the development of fricative production of five- to 11-year-old children with CIs is affected by the children's hearing abilities and late access to auditory information. These limitations however do not prevent the children from eventually reaching a consistency similar to that of children with NH, as suggested by the fact that their production is still evolving during that age span. The results also show that the acquisition of coarticulation strategies can be impeded by degraded or delayed access to audio.

Consonant and Vowel Confusions in Well-Performing Children and Adolescents With Cochlear Implants, Measured by a Nonsense Syllable Repetition Test

Although the majority of early implanted, profoundly deaf children with cochlear implants (CIs), will develop correct pronunciation if they receive adequate oral language stimulation, many of them have difficulties with perceiving minute details of speech. The main aim of this study is to measure the confusion of consonants and vowels in well-performing children and adolescents with CIs. The study also aims to investigate how age at onset of severe to profound deafness influences perception. The participants are 36 children and adolescents with CIs (18 girls), with a mean (SD) age of 11.6 (3.0) years (range: 5.9-16.0 years). Twenty-nine of them are prelingually deaf and seven are postlingually deaf. Two reference groups of normal-hearing (NH) 6- and 13-year-olds are included. Consonant and vowel perception is measured by repetition of 16 bisyllabic vowel-consonant-vowel nonsense words and nine monosyllabic consonant-vowel-consonant nonsense words in an open-set design. For the participants with CIs, consonants were mostly confused with consonants with the same voicing and manner, and the mean (SD) voiced consonant repetition score, 63.9 (10.6)%, was considerably lower than the mean (SD) unvoiced consonant score, 76.9 (9.3)%. There was a devoicing bias for the stops; unvoiced stops were confused with other unvoiced stops and not with voiced stops, and voiced stops were confused with both unvoiced stops and other voiced stops. The mean (SD) vowel repetition score was 85.2 (10.6)% and there was a bias in the confusions of [i:] and [y:]; [y:] was perceived as [i:] twice as often as [y:] was repeated correctly. Subgroup analyses showed no statistically significant differences between the consonant scores for pre- and postlingually deaf participants. For the NH participants, the consonant repetition scores were substantially higher and the difference between voiced and unvoiced consonant repetition scores considerably lower than for the participants with CIs. The participants with CIs obtained scores close to ceiling on vowels and real-word monosyllables, but their perception was substantially lower for voiced consonants. This may partly be related to limitations in the CI technology for the transmission of low-frequency sounds, such as insertion depth of the electrode and ability to convey temporal information.

Vocal Biomarkers of Mild-to-Moderate Hearing Loss in Children and Adults: Voiceless Sibilants

PURPOSE

The purpose of this study was to determine if an objective measure of speech production could serve as a vocal biomarker for the effects of high-frequency hearing loss on speech perception. It was hypothesized that production of voiceless sibilants is governed sufficiently by auditory feedback that high-frequency hearing loss results in subtle but significant shifts in the spectral characteristics of these sibilants.

METHOD

Sibilant production was examined in individuals with mild to moderately severe congenital (22 children; 8-17 years old) and acquired (23 adults; 55-80 years old) hearing losses. Measures of hearing level (pure-tone average thresholds at 4 and 8 kHz), speech perception (detection of nonsense words within sentences), and speech production (spectral center of gravity [COG] for /s/ and /ʃ/) were obtained in unaided and aided conditions.

RESULTS

For both children and adults, detection of nonsense words increased significantly as hearing thresholds improved. Spectral COG for /ʃ/ was unaffected by hearing loss in both listening conditions, whereas the spectral COG for /s/ significantly decreased as high-frequency hearing loss increased. The distance in spectral COG between /s/ and /ʃ/ decreased significantly with increasing hearing level. COG distance significantly predicted nonsense-word detection in children but not in adults.

CONCLUSIONS

At least one aspect of speech production (voiceless sibilants) is measurably affected by high-frequency hearing loss and is related to speech perception in children. Speech production did not predict speech perception in adults, suggesting a more complex relationship between auditory feedback and feedforward mechanisms with age. Even so, these results suggest that this vocal biomarker may be useful for identifying the presence of high-frequency hearing loss in adults and children and for predicting the impact of hearing loss in children.

Patterns of recognition of Arabic consonants by non-native children with cochlear implants and normal hearing

OBJECTIVE

This study examined the patterns of recognition of Arabic consonants, via information transmission analysis for phonological features, in a group of Malay children with normal hearing (NH) and cochlear implants (CI).

METHOD

A total of 336 and 616 acoustic tokens were collected from six CI and 11 NH Malay children, respectively. The groups were matched for hearing age and duration of exposure to Arabic sounds. All the 28 Arabic consonants in the form of consonant-vowel /a/ were presented randomly twice via a loudspeaker at approximately 65 dB SPL. The participants were asked to repeat verbally the stimulus heard in each presentation.

RESULTS

Within the native Malay perceptual space, the two groups responded differently to the Arabic consonants. The dispersed uncategorized assimilation in the CI group was distinct in the confusion matrix (CM), as compared to the NH children. Consonants /ħ/, /tˁ/, /sˁ/ and /ʁ/ were difficult for the CI children, while the most accurate item was /k/ (84%). The CI group transmitted significantly reduced information, especially for place feature transmission, then the NH group (p < 0.001). Significant interactions between place-hearing status and manner-hearing status were also obtained, suggesting there were information transmission differences in the pattern of consonants recognition between the study groups.

CONCLUSION

CI and NH Malay children may be using different acoustic cues to recognize Arabic sounds, which contribute to the different assimilation categories' patterns within the Malay perceptual space.

Realisation of voicing by French-speaking CI children after long-term implant use: An acoustic study

Studies of speech production in French-speaking cochlear-implanted (CI) children are very scarce. Yet, difficulties in speech production have been shown to impact the intelligibility of these children. The goal of this study is to understand the effect of long-term use of cochlear implant on speech production, and more precisely on the coordination of laryngeal-oral gestures in stop production. The participants were all monolingual French children: 13 6;6- to 10;7-year-old CI children and 20 age-matched normally hearing (NH) children. We compared /p/, /t/, /k/, /b/, /d/ and /g/ in word-initial consonant-vowel sequences, produced in isolation in two different tasks, and we studied the effects of CI use, vowel context, task and age factors (i.e. chronological age, age at implantation and duration of implant use). Statistical analyses show a difference in voicing production between groups for voiceless consonants (shorter Voice Onset Times for CI children), with significance reached only for /k/, but no difference for voiced consonants. Our study indicates that in the long run, use of CI seems to have limited effects on the acquisition of oro-laryngeal coordination needed to produce voicing, except for specific difficulties located on velars. In a follow-up study, further acoustic analyses on vowel and fricative production by the same children reveal more difficulties, which suggest that cochlear implantation impacts frequency-based features (second formant of vowels and spectral moments of fricatives) more than durational cues (voicing).

Relationship between auditory perception and vocal production in cochlear implantees: a systematic review

Purpose

To conduct a systematic review of the scientific literature studying the relationship between vocal production and auditory perception in cochlear implant users.

Research strategies

This is an integrative systematic review. The plattforms/databases Bireme, SciELO, Cochrane, Scopus and Web of Science were consulted and the descriptors used were voice, cochlear implant and auditory perception.

Selection criteria

Original papers published in English, French, Spanish or Portuguese involving the study of vocal production and auditory perception in cochlear implant users were selected and there was no restriction about year of publication of the articles.

Data analysis

The studies selected were analyzed according to the author, location, year and publication of the article, as well as for their sample size, type of vocal production and auditory perception assessment and for its major findings and recommendation grade/level of scientific evidence.

Results

The results suggest the existence of positive relationship between vocal production and auditory perception in cochlear implant users, and indicate that the deployment time has a positive influence in this relationship.

Conclusion

None of the selected studies were rated at level 1 of scientific evidence or grade A of recommendation, which is related to the methodological approach that can go with this subject matter. There is great lack of publications relating auditory perception and speech production in cochlear implant users. This gap is even greater when it comes to the adult population.

Phonological Priming in Children with Hearing Loss: Effect of Speech Mode, Fidelity, and Lexical Status

OBJECTIVES

This research determined (1) how phonological priming of picture naming was affected by the mode (auditory-visual [AV] versus auditory), fidelity (intact versus nonintact auditory onsets), and lexical status (words versus nonwords) of speech stimuli in children with prelingual sensorineural hearing impairment (CHI) versus children with normal hearing (CNH) and (2) how the degree of HI, auditory word recognition, and age influenced results in CHI. Note that the AV stimuli were not the traditional bimodal input but instead they consisted of an intact consonant/rhyme in the visual track coupled to a nonintact onset/rhyme in the auditory track. Example stimuli for the word bag are (1) AV: intact visual (b/ag) coupled to nonintact auditory (-b/ag) and 2) auditory: static face coupled to the same nonintact auditory (-b/ag). The question was whether the intact visual speech would "restore or fill-in" the nonintact auditory speech in which case performance for the same auditory stimulus would differ depending on the presence/absence of visual speech.

DESIGN

Participants were 62 CHI and 62 CNH whose ages had a group mean and group distribution akin to that in the CHI group. Ages ranged from 4 to 14 years. All participants met the following criteria: (1) spoke English as a native language, (2) communicated successfully aurally/orally, and (3) had no diagnosed or suspected disabilities other than HI and its accompanying verbal problems. The phonological priming of picture naming was assessed with the multimodal picture word task.

RESULTS

Both CHI and CNH showed greater phonological priming from high than low-fidelity stimuli and from AV than auditory speech. These overall fidelity and mode effects did not differ in the CHI versus CNH-thus these CHI appeared to have sufficiently well-specified phonological onset representations to support priming, and visual speech did not appear to be a disproportionately important source of the CHI's phonological knowledge. Two exceptions occurred, however. First-with regard to lexical status-both the CHI and CNH showed significantly greater phonological priming from the nonwords than words, a pattern consistent with the prediction that children are more aware of phonetics-phonology content for nonwords. This overall pattern of similarity between the groups was qualified by the finding that CHI showed more nearly equal priming by the high- versus low-fidelity nonwords than the CNH; in other words, the CHI were less affected by the fidelity of the auditory input for nonwords. Second, auditory word recognition-but not degree of HI or age-uniquely influenced phonological priming by the AV nonwords.

CONCLUSIONS

With minor exceptions, phonological priming in CHI and CNH showed more similarities than differences. Importantly, this research documented that the addition of visual speech significantly increased phonological priming in both groups. Clinically these data support intervention programs that view visual speech as a powerful asset for developing spoken language in CHI.

Perception of speech features by French-speaking children with cochlear implants

PURPOSE

The present study investigates the perception of phonological features in French-speaking children with cochlear implants (CIs) compared with normal-hearing (NH) children matched for listening age.

METHOD

Scores for discrimination and identification of minimal pairs for all features defining consonants (e.g., place, voicing, manner, nasality) and vowels (e.g., frontness, nasality, aperture) were measured in each listener.

RESULTS

The results indicated no differences in "categorical perception," specified as a similar difference between discrimination and identification between CI children and controls. However, CI children demonstrated a lower level of "categorical precision," that is, lesser accuracy in both feature identification and discrimination, than NH children, with the magnitude of the deficit depending on the feature.

CONCLUSIONS

If sensitive periods of language development extend well beyond the moment of implantation, the consequences of hearing deprivation for the acquisition of categorical perception should be fairly important in comparison to categorical precision because categorical precision develops more slowly than categorical perception in NH children. These results do not support the idea that the sensitive period for development of categorical perception is restricted to the first 1-2 years of life. The sensitive period may be significantly longer. Differences in precision may reflect the acoustic limitations of the cochlear implant, such as coding for temporal fine structure and frequency resolution.

Reading and reading-related skills in children using cochlear implants: prospects for the influence of cued speech

We assessed the reading and reading-related skills (phonemic awareness and phonological short-term memory) of deaf children fitted with cochlear implants (CI), either exposed to cued speech early (before 2 years old) (CS+) or never (CS-). Their performance was compared to that of 2 hearing control groups, 1 matched for reading level (RL), and 1 matched for chronological age (CA). Phonemic awareness and phonological short-term memory were assessed respectively through a phonemic similarity judgment task and through a word span task measuring phonological similarity effects. To assess the use of sublexical and lexical reading procedures, children read pseudowords and irregular words aloud. Results showed that cued speech improved performance on both the phonemic awareness and the reading tasks but not on the phonological short-term memory task. In phonemic awareness and reading, CS+ children obtained accuracy and rapidity scores similar to CA controls, whereas CS- children obtained lower scores than hearing controls. Nevertheless, in phonological short-term memory task, the phonological similarity effect of both CI groups was similar. Overall, these results support the use of cued speech to improve phonemic awareness and reading skills in CI children.

Role of visual speech in phonological processing by children with hearing loss

PURPOSE

This research assessed the influence of visual speech on phonological processing by children with hearing loss (HL).

METHOD

Children with HL and children with normal hearing (NH) named pictures while attempting to ignore auditory or audiovisual speech distractors whose onsets relative to the pictures were either congruent, conflicting in place of articulation, or conflicting in voicing-for example, the picture "pizza" coupled with the distractors "peach," "teacher," or "beast," respectively. Speed of picture naming was measured.

RESULTS

The conflicting conditions slowed naming, and phonological processing by children with HL displayed the age-related shift in sensitivity to visual speech seen in children with NH, although with developmental delay. Younger children with HL exhibited a disproportionately large influence of visual speech and a negligible influence of auditory speech, whereas older children with HL showed a robust influence of auditory speech with no benefit to performance from adding visual speech. The congruent conditions did not speed naming in children with HL, nor did the addition of visual speech influence performance. Unexpectedly, the /wedge/-vowel congruent distractors slowed naming in children with HL and decreased articulatory proficiency.

CONCLUSIONS

Results for the conflicting conditions are consistent with the hypothesis that speech representations in children with HL (a) are initially disproportionally structured in terms of visual speech and (b) become better specified with age in terms of auditorily encoded information.

Early listening and speaking skills predict later reading proficiency in pediatric cochlear implant users

OBJECTIVES

Previous studies have reported that children who use cochlear implants (CIs) tend to achieve higher reading levels than their peers with profound hearing loss who use hearing aids. The purpose of this study was to investigate the influences of auditory information provided by the CI on the later reading skills of children born with profound deafness. The hypothesis was that there would be a positive and predictive relationship between earlier speech perception, production, and subsequent reading comprehension.

DESIGN

The speech perception and production skills at the vowel, consonant, phoneme, and word level of 72 children with prelingual, profound hearing loss were assessed after 48 mos of CI use. The children's reading skills were subsequently assessed using word and passage comprehension measures after an average of 89.5 mos of CI use. A regression analysis determined the amount of variance in reading that could be explained by the variables of perception, production, and socioeconomic status.

RESULTS

Regression analysis revealed that it was possible to explain 59% of the variance of later reading skills by assessing the early speech perception and production performance. The results indicated that early speech perception and production skills of children with profound hearing loss who receive CIs predict future reading achievement skills. Furthermore, the study implies that better early speech perception and production skills result in higher reading achievement. It is speculated that the early access to sound helps to build better phonological processing skills, which is one of the likely contributors to eventual reading success.

Acoustic and perceptual appraisal of speech production in pediatric cochlear implant users

OBJECTIVE

The purpose of the present study was to examine the relationship between objectively measurable acoustic changes in speech production and subjective speech production accuracy and perceived intelligibility immediately following a disruption in auditory feedback normally provided to subjects from a cochlear implant.

METHODS

Six children with profound sensorineural hearing loss participated in the study. Their task was to produce speech samples in two conditions: (1) with auditory feedback from their cochlear implants, and (2) without auditory feedback from their cochlear implants. Samples were subjected to both objective and subjective analyses. Objectively, measures were made of duration, fundamental frequency, and the first and second formants of the vowels. Subjectively, two groups of listeners, one familiar with the speech of children with hearing loss and the other unfamiliar, transcribed the productions and provided ratings of intelligibility.

RESULTS

All the children in this study exhibited significant differences from the cochlear implant-on to the cochlear implant-off condition, although these changes were not always in the predicted direction, nor were they always perceptually salient.

CONCLUSIONS

Consistent with previous studies, children in this investigation demonstrated variable acoustic voice and speech changes following deactivation of their cochlear implant device. Few of these acoustic changes affected speech intelligibility. The results of this study overall suggest that during the initial years following implantation children who are deaf rely to some extent on the auditory feedback provided by a cochlear implant to control and modify F0, duration, and vowel formant production.

Control of voice-onset time in the absence of hearing: a review

The relation between partial or absent hearing and control of the voicing contrast has long been of interest to investigators, in part because speakers who are born deaf characteristically have great difficulty mastering the contrast and in part for the light it can cast on the role of hearing in the acquisition and maintenance of phonological contrasts in general. One of the phonetic characteristics that distinguish voiced from voiceless plosives in English (p/b, t/d, k/g) is voice onset time (VOT): the interval from plosive release to the onset of voicing of the following vowel. This article first reviews research on VOT anomalies in the speech production of prelingually and postlingually deaf speakers. Then it turns to studies of the mechanisms in speech breathing, phonation and articulation that underlie those anomalies. In both populations of speakers, there is a tendency for the difference between voiced and voiceless VOT to be reduced, to the point for many speakers that there is in effect a substitution of the voiced for the voiceless cognate. The separation of the cognate VOTs can be enhanced when some hearing is restored with a cochlear implant. Both populations also present anomalies in speech breathing that can hinder the development of intraoral pressures and transglottal pressure drops that are required for the production of the VOT contrast. Its successful management further requires critical timing among phonatory and articulatory gestures, most of which are not visible, rendering the VOT contrast a particular challenge in the absence of hearing.

Acoustic characteristics of the speech of young cochlear implant users: a comparison with normal-hearing age-mates

OBJECTIVE

The primary objective of this study was to compare select acoustic characteristics of the speech of deaf children who use cochlear implants (young cochlear implant users) with those of children with normal hearing. A secondary objective of this study was to examine the effect, if any, of the deaf child's education (oral versus total communication) on the similarity of these acoustic characteristics to those of normal-hearing age-mates.

DESIGN

Speech was recorded from 181 young cochlear implant users and from 24 children with normal hearing. All speech was produced by imitation, and consisted of complete sentences. Acoustic measures included voice onset time (/t/, /d/), second formant frequency (/i/, /[U0254]/), spectral moments (mean, skew and kurtosis of /s/ and /[U0283]/), a nasal manner metric, and durations (of vowels, words, and sentences).

RESULTS AND DISCUSSION

A large percentage (46 to 97%) of the young cochlear implant users produced acoustic characteristics with values within the range found for children with normal hearing. Exceptions were sentence duration and vowel duration in sentence-initial words, for which only 23 and 25%, respectively, of the COCHLEAR IMPLANT users had values within the normal range. Additionally, for most of the acoustic measures, significantly more COCHLEAR IMPLANT users from oral than from total communication settings had values within the normal range.

CONCLUSIONS

Compared with deaf children with hearing aids (from previous studies by others), deaf children who use cochlear implants have improved speech production skills, as reflected in the acoustic measures of this study. Placement in an oral communication educational setting is also associated with more speech production improvement than placement in a total communication setting.

Receptive and expressive language skills of 106 children with a minimum of 2 years' experience in hearing with a cochlear implant

OBJECTIVE

The aim of the study was to assess the speech development of children with at least 2 years' hearing experience with a cochlear implant (CI).

METHODS

One hundred and six children were tested, all of whom had used the CI for at least 2 years. Receptive and expressive language development were tested using the scales of early communication skills for hearing-impaired children after Geers and Moog and the Reynell developmental language scales III. In addition, free-field audiometry was performed. Pre-postoperative measurements were compared statistically, and a linear regression analysis was carried out.

RESULTS

Clear improvements in the gain in functional hearing 2 years after receiving the CI as well as clear improvements in both speech perception and speech production were ascertained. All deviations were statistically highly significant (P<0.000). The receptive and expressive speech test results correlate positively to a great extent. The results of logistic regressive analysis indicate that the speech production measured depends decisively on age at implantation, age at time of test, speech production before implantation, and additional handicaps.

CONCLUSION

Based on the conception of the WHO, a statistically significant improvement of both impairment and disability can be confirmed. In the present study, the regression analysis established the age at implantation as the most important prognostic factor. While the percentage of children with good speech development is larger with early implanted children than with late implanted children, some of the children among the early implanted group show unsatisfactory speech development of unknown origin. Improvements in speech development are likely to be achieved when more children are diagnosed and implanted early. This finding urgently requires the introduction of a general newborn screening program. Thorough anamnesis and assessment during parent counseling of the manifold factors described are a prerequisite for the precise estimation of the difficulties to be met and the expected effectiveness of the implant in each individual case.

Development of speech perception and production in children with cochlear implants

The purpose of the present study was twofold: 1) to compare the hierarchy of perceived and produced significant speech pattern contrasts in children with cochlear implants, and 2) to compare this hierarchy to developmental data of children with normal hearing. The subjects included 35 prelingual hearing-impaired children with multichannel cochlear implants. The test materials were the Hebrew Speech Pattern Contrast (HeSPAC) test and the Hebrew Picture Speech Pattern Contrast (HePiSPAC) test for older and younger children, respectively. The results show that 1) auditory speech perception performance of children with cochlear implants reaches an asymptote at 76% (after correction for guessing) between 4 and 6 years of implant use; 2) all implant users perceived vowel place extremely well immediately after implantation; 3) most implanted children perceived initial voicing at chance level until 2 to 3 years after implantation, after which scores improved by 60% to 70% with implant use; 4) the hierarchy of phonetic-feature production paralleled that of perception: vowels first, voicing last, and manner and place of articulation in between; and 5) the hierarchy in speech pattern contrast perception and production was similar between the implanted and the normal-hearing children, with the exception of the vowels (possibly because of the interaction between the specific information provided by the implant device and the acoustics of the Hebrew language). The data reported here contribute to our current knowledge about the development of phonological contrasts in children who were deprived of sound in the first few years of their lives and then developed phonetic representations via cochlear implants. The data also provide additional insight into the interrelated skills of speech perception and production.

Phonetic inventory development in young cochlear implant users 6 years postoperation

Increases in the phonetic inventories of a group of 9 children in the fifth and sixth years of experience with a cochlear implant are reported, extending a previous 4-year study (T. A. Serry & P. J. Blamey, 1999). Thirty-six out of 44 phones in Australian English reached the criterion of 50% correct in the conversational samples of 5 or more children. This level of performance corresponds to intelligible, but not completely natural, speech. The rate of improvement in the sixth year was slow, indicating a probable plateau in performance. The 8 phones that did not attain the 50% criterion in 5 or more children were /see text/. Potential reasons for the slow development or nondevelopment of these phones include very low frequency of occurrence for /see text/ and the perceptual and articulatory characteristics of /see text/. /see text/ is also subject to a high degree of allophonic variation in the fluent speech of normally hearing speakers, probably accounting for much of the variability in its articulation in the conversational samples.

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.

Determinants of speech perception in children after cochlear implantation

BACKGROUND

Cochlear implants provide access to the speech signal in those profoundly deaf children who derive no material benefit from acoustic hearing aids. Speech perception after implantation can vary widely--we have analysed the contribution of several factors.

METHODS

We examined 40 children with mean age at implantation of 52 months who were either born deaf or became deaf before 3 years. All patients received the same multichannel implant system and were followed up for 5 years. We used connected discourse tracking (CDT) as the measure of speech perception. The effect of five potential predictors (age at implantation, number of inserted electrodes, origin of deafness, mode of communication, and socioeconomic group) on speech perception was analysed.

FINDINGS

The mean number of words per minute perceived increased from 0 before implantation to 44.8 (SD 24.3) 5 years after implantation. Repeated-measures ANOVA showed that children significantly progressed over time (p=0.001). Age at implantation was a significant covariate (p=0.01) and mode of communication was a significant between-individuals factor (p=0.04).

INTERPRETATION

Young age at intervention and oral communication mode are the most important known determinants of later speech perception in young children after cochlear implantation. Early identification of candidate children necessitates implementation of universal neonatal screening programmes for hearing impairment.

Cochlear implants in young children: the relationship between speech perception and speech intelligibility

OBJECTIVE

To determine the relationship between measures of speech perception and speech production after cochlear implantation of young children with profound congenital and prelingual deafness.

DESIGN

A prospective study was undertaken on a consecutive group of children with profound deafness. There were 126 children at the preimplantation interval and 71, 50, 26, and 20 children, respectively, at the 2, 3, 4, and 5 yr follow-up after implantation. Speech perception and speech intelligibility were assessed using hierarchical rating scales. Spearman rank correlation coefficients were used to determine the statistical correlations. All patients were either congenitally deaf or deafened before the age of 3 yr and were implanted before age 7 yr. The patients all received the Nucleus multichannel cochlear implant system with the most appropriate speech encoding strategy.

RESULTS

Speech intelligibility at 5 yr was strongly correlated with speech perception at the 2, 3, 4, and 5 yr intervals after implantation (Spearman coefficients 0.77, 0.81, 0.58, 0.58; p < or = 0.01). Speech intelligibility at the 2, 3, and 4 yr intervals also correlated in a similar manner with earlier speech perception abilities (p < or = 0.01).

CONCLUSIONS

The results suggest that speech intelligibility between 2 and 5 yr after implantation in young children with congenital and prelingual profound deafness can be predicted by measures of earlier speech perception.

The effect of auditory feedback on the control of oral-nasal balance by pediatric cochlear implant users

OBJECTIVE

This study examined the control of oral-nasal balance by pediatric cochlear implant (CI) users, with and without auditory feedback.

DESIGN

Five CI users read lists of sentences in two conditions: with their devices on and with their devices off. Their oral-nasal balance (ratio of energy radiated from the oral and nasal cavities) was measured in both conditions and compared with values obtained from children with normal hearing.

RESULTS

CI users showed different patterns of abnormal oral-nasal balance with their devices off, but they generally achieved values that were closer to normal when their devices were on.

CONCLUSIONS

The results suggest that children with CIs use the auditory signal provided by their device to improve their control of nasalization. It is also possible that at least part of the changes in oral-nasal balance were driven by changes in related articulatory parameters.

Imitative consonant feature production by children with multichannel sensory aids

OBJECTIVE

To examine changes over time in consonant feature production by children with profound hearing impairments who used either the Nucleus multichannel cochlear implant or the multichannel vibrotactile aid, Tactaid 7.

DESIGN

Imitative consonant productions of children with prelingual deafness were elicited and transcribed at two intervals: 1) before receiving their respective devices (predevice interval), and 2) after an average of 1.5 yr of device use (postdevice interval). The consonant productions were analyzed in terms of the percentage of consonant features (manner, place, and voicing) produced by the child that matched the features of the examiner's target. The percentage of features produced correctly was then averaged across repetitions, vowel environments, and participants within each group.

RESULTS

At the predevice interval, the cochlear implant and Tactaid 7 participants demonstrated similar imitative consonant production abilities. After an average of 1.5 yr of device use, the cochlear implant participants demonstrated significantly greater gains than did the Tactaid 7 participants for the features of voicing and place of articulation. Although the cochlear implant participants showed a trend towards better production of the consonant manner features, this difference failed to reach significance.

CONCLUSIONS

The current results suggest that the use of a multichannel sensory aid yields improvements in consonant feature production. Furthermore, use of a cochlear implant appears to promote the production of consonant voicing and place features to a greater degree than does the use of a multichannel tactile aid.