Assessing consonant production in children with cochlear implants.

OBJECTIVE: The objective of this study was to investigate the development of consonant inventory and accuracy in pediatric cochlear implant (CI) recipients and compare their performance to typical hearing (TH) children. METHODS: One hundred and twenty nine children with CIs, implanted between 6-38 months of age, and 30 age-matched children with TH participated in this study. Spontaneous speech samples were collected at 3.5 and 4.5 years chronological age and the first 100 different words spoken by each participant were transcribed. Two consonant production measures were subsequently calculated to assess consonant acquisition and mastery. The percentage of Consonants Correct (CC) was used for measuring accuracy and Consonant Diversity (CD), an inventory measure, was used to identify the number of different consonants spoken by each participant. Repeated measures analyses of variance were conducted to examine the differences in consonant production scores based on presence of CI (participants with CI versus typical hearing (TH) participants), and chronological age at data collection (3.5 years versus 4.5 years). RESULTS: CI recipients displayed lower consonant production scores compared to TH children. Children with the most device experience (32-38 months at 3.5 years) performed on par with their TH peers. CONCLUSIONS: The two measures used in this study together appear capable of comprehensively describing the changes in consonant production skills of children. Results from this study indicate that while most CI participants display lower scores compared to TH children, many of the CI users are able to produce speech sounds on par with TH children.

The Lombard effect observed in speech produced by cochlear implant users in noisy environments: A naturalistic study.

The Lombard effect is an involuntary response speakers experience in the presence of noise during voice communication. This phenomenon is known to cause changes in speech production such as an increase in intensity, pitch structure, formant characteristics, etc., for enhanced audibility in noisy environments. Although well studied for normal hearing listeners, the Lombard effect has received little, if any, attention in the field of cochlear implants (CIs). The objective of this study is to analyze speech production of CI users who are postlingually deafened adults with respect to environmental context. A total of six adult CI users were recruited to produce spontaneous speech in various realistic environments. Acoustic-phonetic analysis was then carried out to characterize their speech production in these environments. The Lombard effect was observed in the speech production of all CI users who participated in this study in adverse listening environments. The results indicate that both suprasegmental (e.g., F0, glottal spectral tilt and vocal intensity) and segmental (e.g., F1 for /i/ and /u/) features were altered in such environments. The analysis from this study suggests that modification of speech production of CI users under the Lombard effect may contribute to some degree an intelligible communication in adverse noisy environments.

Prior exposure to a reverberant listening environment improves speech intelligibility in adult cochlear implant listeners.

OBJECTIVES: The goal of this study is to investigate whether prior exposure to reverberant listening environment improves speech intelligibility of adult cochlear implant (CI) users. METHODS: Six adult CI users participated in this study. Speech intelligibility was measured in five different simulated reverberant listening environments with two different speech corpuses. Within each listening environment, prior exposure was varied by either having the same environment across all trials (blocked presentation) or having different environment from trial to trial (unblocked). RESULTS: Speech intelligibility decreased as reverberation time increased. Although substantial individual variability was observed, all CI listeners showed an increase in the blocked presentation condition as compared to the unblocked presentation condition for both speech corpuses. CONCLUSION: Prior listening exposure to a reverberant listening environment improves speech intelligibility in adult CI listeners. Further research is required to understand the underlying mechanism of adaptation to listening environment.

Self-esteem in children and adolescents with hearing loss.

Children with hearing loss are at risk for lower self-esteem due to differences from hearing peers relative to communication skills, physical appearance, and social maturity. This study examines the influence of generic factors unrelated to hearing loss (e.g., age, gender, temperament) and specific factors associated with hearing loss (e.g., age at identification, communication skills) on how children with hearing loss wearing cochlear implants or hearing aids appraise self-esteem. Fifty children with hearing loss wearing cochlear implants or hearing aids participated (Mean age: 12.88 years; mean duration of device use: 3.43 years). Participants independently completed online questionnaires to assess communication skills, social engagement, self-esteem, and temperament. Children with hearing loss rated global self-esteem significantly more positively than hearing peers, t = 2.38, p = .02. Self-esteem ratings attained significant positive correlations with affiliation (r = .42, p = .002) and attention (r = .45, p = .001) temperaments and a significant negative association with depressive mood (r = - .60, p < .0001). No significant correlations emerged between self-esteem and demographic factors, communication skills, or social engagement. Because successful communication abilities do not always co-occur with excellent quality of life, clinicians and professionals working with children with hearing loss need to understand components contributing to self-esteem to improve identification, counseling, and external referrals for children in this population.

Evaluation of adaptive dynamic range optimization in adverse listening conditions for cochlear implants.

The aim of this study is to investigate the effect of Adaptive Dynamic Range Optimization (ADRO) on speech identification for cochlear implant (CI) users in adverse listening conditions. In this study, anechoic quiet, noisy, reverberant, noisy reverberant, and reverberant noisy conditions are evaluated. Two scenarios are considered when modeling the combined effects of reverberation and noise: (a) noise is added to the reverberant speech, and (b) noisy speech is reverberated. CI users were tested in different listening environments using IEEE sentences presented at 65 dB sound pressure level. No significant effect of ADRO processing on speech intelligibility was observed.

Assessment of health-related quality of life 6 years after childhood cochlear implantation.

PURPOSE: To examine the impact of cochlear implant (CI) intervention on health-related quality of life (HRQOL) assessed by both self- and parent-reported measures. METHODS: In this national study of children implanted between ages 6 months and 5 years, HRQOL of 129 children 6-year post-CI was compared to 62 internal study (NH1) and 185 external (NH2) samples of hearing children frequency-matched to the CI group on sociodemographic variables. HRQOL ratings of children and their parents in each group, measured using the Child Health and Illness Profile-Child Edition, were compared, and their associations with the Family Stress Scale were investigated. RESULTS: CI children reported overall and domain-specific HRQOL that was comparable to both NH1 and NH2 peers. CI parents reported worse child scores than NH1 parents in Achievement, Resilience, and Global score (p's < 0.01) but similar or better scores than socioeconomically comparable NH2 parents. Higher family stress was negatively associated with all parent-reported HRQOL outcomes (p's < 0.01). Parent-child correlations in HRQOL global scores trended higher in CI recipients (r = 0.50) than NH1 (r = 0.42) and NH2 (r = 0.35) controls. CONCLUSIONS: CI recipients report HRQOL comparable to NH peers. These results, from both child and parent perspective, lend support to the effectiveness of CI intervention in mitigating the impact of early childhood deafness. Family stress was associated with worse HRQOL, underscoring a potential therapeutic target. Parent-child agreement in HRQOL scores was higher for CI families than NH families, which may reflect higher caregiver insight and involvement related to the CI intervention.

Age-dependent cost-utility of pediatric cochlear implantation.

OBJECTIVES: Cochlear implantation (CI) has become the mainstay of treatment for children with severe-to-profound sensorineural hearing loss (SNHL). Yet, despite mounting evidence of the clinical benefits of early implantation, little data are available on the long-term societal benefits and comparative effectiveness of this procedure across various ages of implantation-a choice parameter for parents and clinicians with high prognostic value for clinical outcome. As such, the aim of the present study is to evaluate a model of the consequences of the timing of this intervention from a societal economic perspective. Average cost utility of pediatric CI by age at intervention will be analyzed. DESIGN: Prospective, longitudinal assessment of health utility and educational placement outcomes in 175 children recruited from six U.S. centers between November 2002 and December 2004, who had severe-to-profound SNHL onset within 1 year of age, underwent CI before 5 years of age, and had up to 6 years of postimplant follow-up that ended in November 2008 to December 2011. Costs of care were collected retrospectively and stratified by preoperative, operative, and postoperative expenditures. Incremental costs and benefits of implantation were compared among the three age groups and relative to a nonimplantation baseline. RESULTS: Children implanted at <18 months of age gained an average of 10.7 quality-adjusted life years (QALYs) over their projected lifetime as compared with 9.0 and 8.4 QALYs for those implanted between 18 and 36 months and at >36 months of age, respectively. Medical and surgical complication rates were not significantly different among the three age groups. In addition, mean lifetime costs of implantation were similar among the three groups, at approximately $2000/child/year (77.5-year life expectancy), yielding costs of $14,996, $17,849, and $19,173 per QALY for the youngest, middle, and oldest implant age groups, respectively. Full mainstream classroom integration rate was significantly higher in the youngest group at 81% as compared with 57 and 63% for the middle and oldest groups, respectively (p < 0.05) after 6 years of follow-up. After incorporating lifetime educational cost savings, CI led to net societal savings of $31,252, $10,217, and $6,680 for the youngest, middle, and oldest groups at CI, respectively, over the child's projected lifetime. CONCLUSIONS: Even without considering improvements in lifetime earnings, the overall cost-utility results indicate highly favorable ratios. Early (<18 months) intervention with CI was associated with greater and longer quality-of-life improvements, similar direct costs of implantation, and economically valuable improved classroom placement, without a greater incidence of medical and surgical complications when compared to CI at older ages.

Influence of implantation age on school-age language performance in pediatric cochlear implant users.

OBJECTIVE: This study examined specific spoken language abilities of 160 children with severe-to-profound sensorineural hearing loss followed prospectively 4, 5, or 6 years after cochlear implantation. STUDY SAMPLE: Ninety-eight children received implants before 2.5 years, and 62 children received implants between 2.5 and 5 years of age. DESIGN: Language was assessed using four subtests of the Comprehensive Assessment of Spoken Language (CASL). Standard scores were evaluated by contrasting age of implantation and follow-up test time. RESULTS: Children implanted under 2.5 years of age achieved higher standard scores than children with older ages of implantation for expressive vocabulary, expressive syntax, and pragmatic judgments. However, in both groups, some children performed more than two standard deviations below the standardization group mean, while some scored at or well above the mean. CONCLUSIONS: Younger ages of implantation are associated with higher levels of performance, while later ages of implantation are associated with higher probabilities of continued language delays, particularly within subdomains of grammar and pragmatics. Longitudinal data from this cohort study demonstrate that after 6 years of implant experience, there is large variability in language outcomes associated with modifiers of rates of language learning that differ as children with implants age.

A comparative study of psychosocial development in children who receive cochlear implants.

OBJECTIVES: This study assessed self-reported quality of life of children with a cochlear implant (CI), comparing results with two published reports from the past decade. METHODS: Participants included 33 pediatric CI recipients with a mean age of 10.12 years (SD = 3.59), mean implantation age of 1.36 years (SD = 0.46), and mean CI experience of 6.23 years (SD = 1.75). Children in all three studies completed a self-report quality-of-life questionnaire that included seven benefit and six problem items, rated on a 5-point Likert scale. RESULTS: Outcomes revealed agreement across studies in overall benefit and problem ratings. Environmental awareness and frustration reduction were the most and least positively rated outcomes, respectively. Items contributing to overall ratings differed across studies. Current CI recipients rated speech production, making new friends, and understanding speech more positively and taking extra care of the device more negatively than previous generations of pediatric CI users. DISCUSSION: Overall, benefits outweigh problems of the device, according to children using CI. Differences in issues motivating self-report ratings reflect changes in CI candidacy, technology, and social participation over the past decade. These findings emphasize the need for clinicians to address not only communication needs, but also quality-of-life issues to optimize outcomes in children using CI.

Cochlear implantation updates: the Dallas Cochlear Implant Program.

This report provides an overview of many research projects conducted by the Dallas Cochlear Implant Program, a joint enterprise between the University of Texas at Dallas, the University of Texas Southwestern Medical Center, and Children's Medical Center. The studies extend our knowledge of factors influencing communication outcomes in users of cochlear implants. Multiple designs and statistical techniques are used in the studies described including both cross sectional and longitudinal analyses. Sample sizes vary across the studies, and many of the samples represent large populations of children from North America. Multiple statistical techniques are used by the team to analyze outcomes. The team has provided critical information regarding electrode placement, signal processing, and communication outcomes in users of cochlear implants.

Timing of cochlear implantation and parents' global ratings of children's health and development.

OBJECTIVE: To assess children's health-related quality of life (HRQL) and development after cochlear implant (CI) surgery and compare improvements between different age of implantation categories. STUDY DESIGN: Prospective, longitudinal study comparing outcomes of deaf children post-CI with hearing controls. SETTING: Six US CI centers. PATIENTS: Deaf children who received CI (n = 188) and hearing children of comparable ages (n = 97). INTERVENTION: CI before 5 years of age. MAIN OUTCOME MEASURE: Parental ratings of global HRQL and development, as assessed over the first 4 years of follow-up using visual analog scales. Development scores assess parental views of children's growth and development, motor skills, ability to express themselves and communicate with others, and learning abilities. Associations of baseline child and family characteristics with post-CI HRQL and development were investigated using multivariable analysis, controlling for factors that influence post-CI language learning. RESULTS: Baseline deficits of CI candidates relative to hearing controls were larger in development than HRQL. Development scores improved significantly by 4 years after CI, particularly in the youngest CI recipients. Developmental deficits of older CI recipients with early, extended hearing aid use were only partially remediated by CI. Overall, no significant health deficits were observed in CI children after 4 years. Cognition and speech recognition were positively associated with both HRQL and development. CONCLUSION: Parental perspectives on quality of their child's life and development provide practical insight into the optimal timing of interventions for early-onset deafness. Validity of parental global assessments is supported by clinical measures of speech perception and language learning and comparison with a well-validated health status instrument.

Language development after cochlear implantation: an epigenetic model.

Growing evidence supports the notion that dynamic gene expression, subject to epigenetic control, organizes multiple influences to enable a child to learn to listen and to talk. Here, we review neurobiological and genetic influences on spoken language development in the context of results of a longitudinal trial of cochlear implantation of young children with severe to profound sensorineural hearing loss in the Childhood Development after Cochlear Implantation study. We specifically examine the results of cochlear implantation in participants who were congenitally deaf (N = 116). Prior to intervention, these participants were subject to naturally imposed constraints in sensory (acoustic-phonologic) inputs during critical phases of development when spoken language skills are typically achieved rapidly. Their candidacy for a cochlear implant was prompted by delays (n = 20) or an essential absence of spoken language acquisition (n = 96). Observations thus present an opportunity to evaluate the impact of factors that influence the emergence of spoken language, particularly in the context of hearing restoration in sensitive periods for language acquisition. Outcomes demonstrate considerable variation in spoken language learning, although significant advantages exist for the congenitally deaf children implanted prior to 18 months of age. While age at implantation carries high predictive value in forecasting performance on measures of spoken language, several factors show significant association, particularly those related to parent-child interactions. Importantly, the significance of environmental variables in their predictive value for language development varies with age at implantation. These observations are considered in the context of an epigenetic model in which dynamic genomic expression can modulate aspects of auditory learning, offering insights into factors that can influence a child's acquisition of spoken language after cochlear implantation. Increased understanding of these interactions could lead to targeted interventions that interact with the epigenome to influence language outcomes with intervention, particularly in periods in which development is subject to time-sensitive experience.

Long-term outcomes of cochlear implantation in early childhood: sample characteristics and data collection methods.

OBJECTIVES: This article describes participants in a follow-up study of a nationwide sample of children who had used a cochlear implant (CI) since preschool. The children were originally tested when they were in early elementary grades, and results were published in a monograph supplement of Ear and Hearing. Recently, many of these children returned for follow-up testing when they were in high school with >10 yrs experience with a CI. This introductory article will (1) discuss the extent to which the sample tested is representative of typical populations and (2) describe how sample characteristics changed over time for the 112 students tested in both elementary grades and high school. DESIGN: Over a 4-yr period, 112 teenagers from across North America, accompanied by a parent, attended a research camp that was similar to one in which they had participated 8 yrs earlier. A battery of auditory, speech, language, and reading tests was administered, and responses to questionnaires and written language samples were obtained and are described in the following articles in this issue. This article summarizes child, family, and educational characteristics that were quantified so that their role in outcome levels achieved could be examined statistically. For example, metrics were devised to reflect the extent to which a student's language improved when sign language was added to spoken language (i.e., sign enhancement) based on test results obtained in elementary grades and in high school. RESULTS: Comparisons of early characteristics of the 112 students who returned for follow-up testing with the 72 who did not return indicated comparable Performance Intelligence Quotients, communication mode ratings, family education/income, and age at implant. However, follow-up participants had better speech perception, speech intelligibility, and language skills at 8 or 9 yrs of age. Seventy-five percent of returning teenagers were fully mainstreamed in high school (compared with 63% in elementary grades). Only 5% of adolescents were in full-time special education. Grade placement of the teenagers was appropriate to their chronologic age. Estimates of sign enhancement, family characteristics, and Performance Intelligence Quotient were consistent over the two test sessions. CONCLUSIONS: A large proportion of the original sample returned for follow-up testing in adolescence, but they were a more selective group than nonreturning subjects, and their scores may overestimate long-term CI outcomes for the general population. On the other hand, CI-HS students who participated in this study received their device >10 yrs ago and did not have some of the advantages available to more recently implanted children, so their results may underestimate those outcomes.

Factors contributing to speech perception scores in long-term pediatric cochlear implant users.

OBJECTIVES: The objectives of this report are to (1) describe the speech perception abilities of long-term pediatric cochlear implant (CI) recipients by comparing scores obtained at elementary school (CI-E, 8 to 9 yrs) with scores obtained at high school (CI-HS, 15 to 18 yrs); (2) evaluate speech perception abilities in demanding listening conditions (i.e., noise and lower intensity levels) at adolescence; and (3) examine the relation of speech perception scores to speech and language development over this longitudinal timeframe. DESIGN: All 112 teenagers were part of a previous nationwide study of 8- and 9-yr-olds (N = 181) who received a CI between 2 and 5 yrs of age. The test battery included (1) the Lexical Neighborhood Test (LNT; hard and easy word lists); (2) the Bamford Kowal Bench sentence test; (3) the Children's Auditory-Visual Enhancement Test; (4) the Test of Auditory Comprehension of Language at CI-E; (5) the Peabody Picture Vocabulary Test at CI-HS; and (6) the McGarr sentences (consonants correct) at CI-E and CI-HS. CI-HS speech perception was measured in both optimal and demanding listening conditions (i.e., background noise and low-intensity level). Speech perception scores were compared based on age at test, lexical difficulty of stimuli, listening environment (optimal and demanding), input mode (visual and auditory-visual), and language age. RESULTS: All group mean scores significantly increased with age across the two test sessions. Scores of adolescents significantly decreased in demanding listening conditions. The effect of lexical difficulty on the LNT scores, as evidenced by the difference in performance between easy versus hard lists, increased with age and decreased for adolescents in challenging listening conditions. Calculated curves for percent correct speech perception scores (LNT and Bamford Kowal Bench) and consonants correct on the McGarr sentences plotted against age-equivalent language scores on the Test of Auditory Comprehension of Language and Peabody Picture Vocabulary Test achieved asymptote at similar ages, around 10 to 11 yrs. CONCLUSIONS: On average, children receiving CIs between 2 and 5 yrs of age exhibited significant improvement on tests of speech perception, lipreading, speech production, and language skills measured between primary grades and adolescence. Evidence suggests that improvement in speech perception scores with age reflects increased spoken language level up to a language age of about 10 yrs. Speech perception performance significantly decreased with softer stimulus intensity level and with introduction of background noise. Upgrades to newer speech processing strategies and greater use of frequency-modulated systems may be beneficial for ameliorating performance under these demanding listening conditions.

Factors influencing speech production in elementary and high school-aged cochlear implant users.

OBJECTIVES: The objectives of this study were to (a) evaluate changes in speech intelligibility in a group of 110 adolescent users of cochlear implants who were first assessed in elementary school (CI-E) and later in high school (CI-HS) and (b) examine factors influencing speech intelligibility performance at the CI-E and CI-HS sessions. DESIGN: Participants were 110 adolescents who participated in an earlier study examining 181 young elementary school-aged children. Primary outcome measures included speech intelligibility under quiet and multispeaker background conditions and consonants correct produced in the sentences. Multiple linear regressions were used to evaluate how participant, family, and performance measures influenced their speech production during adolescence. Performance measures included estimates of speech perception, working memory, sign enhancement, and duration of seven-syllable sentences. Participant and family measures included duration of deafness, performance intelligence quotients, gender, family size, and socioeconomic status. Principal component analyses were used to construct common variables across highly intercorrelated measures. Three sets of multiple linear regressions evaluated the contributions of the variables to the variance associated with adolescent speech intelligibility. RESULTS: Speech intelligibility and consonants correct significantly increased nearly 22% between the two test sessions. Speech intelligibility significantly decreased by approximately 20% in the multispeaker babble condition relative to the quiet condition. Duration of seven-syllable sentences significantly decreased during the two test sessions. Data revealed that 65.8% of the variance in adolescent speech intelligibility was predicted from participant, family, and performance measures observed in elementary school. Forty-nine percent of the variance at adolescence was accounted for by the participant, family, and performance measures observed during the high school test session. Evaluation of variance including participant and family measures at both time periods, in conjunction with the adolescent performance measures, accounted for 49% of the variance in adolescence performance. After contributions from participant and family variables at the elementary and adolescent test sessions were removed, 21% of the variance in adolescent speech intelligibility was due to the performance measures at adolescence. Independent predictors of performance at adolescence included negative effects of sign enhancement and duration of seven-syllable sentences. CONCLUSIONS: Substantial improvements were made in consonant accuracy, sentence duration, and speech intelligibility between elementary and high school test sessions. Reductions in speech intelligibility performance suggest that allophonic variations, distortions, or use of speech sounds in a nonambient language may contribute to the reductions observed in multispeaker background conditions. Although a significant amount of variance in adolescent performance is accounted for by participant and family characteristics, elementary school speech production and an early reliance on speaking and listening independently account for variance in adolescence speech intelligibility. Over and beyond all the contributions made by participant, family and performance measures, greater reliance on oral communication, and shorter sentence durations independently account for variance at adolescence.

Epilogue: factors contributing to long-term outcomes of cochlear implantation in early childhood.

OBJECTIVES: This report focuses on how speech perception, speech production, language, and literacy performance in adolescence are influenced by a common set of predictor variables obtained during elementary school in a large group of teenagers using cochlear implants (CIs). DESIGN: Time-lag analyses incorporating seven common predictor variables associated with the elementary school test period were evaluated. The elementary school-age variables included five contributors across the performance domains: gender, performance intelligence quotient, family size, socioeconomic status, and duration of deafness (operationally defined as the time period between the age of implantation and the onset of deafness). Regression analyses then examined how communication mode in early elementary grades influenced skills exhibited in high school and how this influence was mediated by information capacity of immediate memory. RESULTS: High correlations occurred between outcome measures collected at CI-E session and similar measures collected at CI-HS (values ranging from 0.75 to 0.83), indicating that the relative standing of individuals on these outcomes is highly stable over time. The best performers in elementary grades exhibit the best outcomes in high school, and early difficulties tend to persist throughout the elementary and high school years. The most highly related outcome areas were language and reading/literacy (values ranging from 0.74 to 0.88). These skills seem closely linked, and CI children who demonstrate the best vocabulary and syntax skills in elementary grades achieved the highest literacy performance in high school. Speech perception and speech production skills are also highly correlated with one another (r = 0.69 to 0.87), suggesting that the most direct result of improved auditory input from a CI is the child's ability to produce intelligible speech. The lowest correlations are observed between reading/literacy and speech perception (r = 0.30 to 0.54) or speech production (values ranging from 0.31 to 0.58). CI-E verbal rehearsal speed is an independent and powerful predictor of each early performance outcome, accounting for between 13% and 30% of the variance in early outcomes above and beyond that accounted for by gender, family size, socioeconomic status, performance intelligence quotient, duration of deafness, and the CI-E sign enhancement ratio. Group mean scores for language, reading, and social adjustment were generally within an SD of normative samples of typically developing age-mates with normal hearing. CONCLUSIONS: Use of sign to enhance spoken communication negatively influenced verbal rehearsal speed, which was a strong predictor of all early outcomes, which in turn strongly influenced later outcomes. These analyses suggest that early communication mode exerts a powerful influence on early outcomes that persist into later years. Speech perception, speech intelligibility, language, literacy, and psychosocial adjustment far exceeded that reported for similar groups before the advent of CI technology.

Article 1: Long-Term outcomes of cochlear implantation in early childhood: Sample characteristics and data collection methods.

Articles contained in this monograph describe the communication performance of 112 teenagers who received multichannel cochlear implants between the ages of 2 and 5 years. Children were first tested during the elementary school years when they were 8 or 9 years of age. They also were tested as adolescents when they were between 15 and 18 years old. Characteristics of the population are described including their modes of communication and educational environments. Child, family and educational variables that will be explored in the following articles as possible predictors of successful outcomes are introduced.