Ann E. Geers

Factors associated with development of speech production skills in children implanted by age five.

Objective This study investigated factors contributing to speech perception outcomes in children with prelingual deafness after 4 to 7 yr of multichannel cochlear implant use. The analysis controlled for the effects of child, family and implant characteristics so that educational factors most conducive to maximum implant benefit could be identified. Design One hundred eighty-one 8- and 9-yr-old children from across the US and Canada who received a cochlear implant by age 5 were administered a battery of speech perception tests. Type and amount of educational intervention since implantation constituted the independent variables. Characteristics of the child, the family, and the implant itself constituted intervening variables. A series of multiple regression analyses determined the amount of variance in speech perception ability accounted for by the intervening variables and the amount of additional variance attributable to independent variables. Results The children achieved an average level of about 50% open-set speech perception through listening alone and almost 80% through lipreading and listening together, but with scores for individual children ranging from 0 to 100% correct. Over half of the variance in speech perception scores was predicted by characteristics of the child, family, implant and educational program. Significant predictors of good speech perception included greater nonverbal intelligence, smaller family size, longer use of the updated SPEAK/CIS processing strategy, a fully active electrode array, greater electrical dynamic range between threshold and maximum comfort level, and greater growth of loudness with increasing stimulus intensity. After the variance due to these variables was controlled, the primary rehabilitative factor associated with good speech perception skill development was educational emphasis on oral-aural communication. Conclusions Children with profound hearing loss achieved unprecedented levels of speech perception skill 4 to 7 yr after cochlear implantation. Use of an updated speech processor, such as SPEAK, contributed significantly to improved speech perception skills, even in children who were initially fitted with an earlier strategy, such as M-PEAK. In addition, the audiologist who programs the cochlear implant makes an important contribution to the child’s successful outcome with the device. A well-fitted map, as evidenced by a wide dynamic range and optimal growth of loudness characteristics, contributed substantially to the child’s ability to hear speech. Finally, the classroom communication mode used in the child’s school affects speech perception outcome. Children whose educational program emphasized dependence on speech and audition for communication were better able to use the information provided by the implant to understand speech.

Effects of Early Auditory Experience on the Spoken Language of Deaf Children at 3 Years of Age

Objective: By age 3, typically developing children have achieved extensive vocabulary and syntax skills that facilitate both cognitive and social development. Substantial delays in spoken language acquisition have been documented for children with severe to profound deafness, even those with auditory oral training and early hearing aid use. This study documents the spoken language skills achieved by orally educated 3-yr-olds whose profound hearing loss was identified and hearing aids fitted between 1 and 30 mo of age and who received a cochlear implant between 12 and 38 mo of age. The purpose of the analysis was to examine the effects of age, duration, and type of early auditory experience on spoken language competence at age 3.5 yr. Design: The spoken language skills of 76 children who had used a cochlear implant for at least 7 mo were evaluated via standardized 30-minute language sample analysis, a parent-completed vocabulary checklist, and a teacher language-rating scale. The children were recruited from and enrolled in oral education programs or therapy practices across the United States. Inclusion criteria included presumed deaf since birth, English the primary language of the home, no other known conditions that interfere with speech/language development, enrolled in programs using oral education methods, and no known problems with the cochlear implant lasting more than 30 days. Results: Strong correlations were obtained among all language measures. Therefore, principal components analysis was used to derive a single Language Factor score for each child. A number of possible predictors of language outcome were examined, including age at identification and intervention with a hearing aid, duration of use of a hearing aid, pre-implant pure-tone average (PTA) threshold with a hearing aid, PTA threshold with a cochlear implant, and duration of use of a cochlear implant/age at implantation (the last two variables were practically identical because all children were tested between 40 and 44 mo of age). Examination of the independent influence of these predictors through multiple regression analysis revealed that pre-implant–aided PTA threshold and duration of cochlear implant use (i.e., age at implant) accounted for 58% of the variance in Language Factor scores. A significant negative coefficient associated with pre-implant–aided threshold indicated that children with poorer hearing before implantation exhibited poorer language skills at age 3.5 yr. Likewise, a strong positive coefficient associated with duration of implant use indicated that children who had used their implant for a longer period of time (i.e., who were implanted at an earlier age) exhibited better language at age 3.5 yr. Age at identification and amplification was unrelated to language outcome, as was aided threshold with the cochlear implant. A significant quadratic trend in the relation between duration of implant use and language score revealed a steady increase in language skill (at age 3.5 yr) for each additional month of use of a cochlear implant after the first 12 mo of implant use. The advantage to language of longer implant use became more pronounced over time. Conclusions: Longer use of a cochlear implant in infancy and very early childhood dramatically affects the amount of spoken language exhibited by 3-yr-old, profoundly deaf children. In this sample, the amount of pre-implant intervention with a hearing aid was not related to language outcome at 3.5 yr of age. Rather, it was cochlear implantation at a younger age that served to promote spoken language competence. The previously identified language-facilitating factors of early identification of hearing impairment and early educational intervention may not be sufficient for optimizing spoken language of profoundly deaf children unless it leads to early cochlear implantation.

Spoken Language Scores of Children Using Cochlear Implants Compared to Hearing Age-Mates at School Entry

This study investigated three questions: Is it realistic to expect age-appropriate spoken language skills in children with cochlear implants (CIs) who received auditory-oral intervention during the preschool years? What characteristics predict successful spoken language development in this population? Are children with CIs more proficient in some areas of language than others? We analyzed language skills of 153 children with CIs as measured by standardized tests. These children (mean age = 5 years and 10 months) attended programs in the United States (N = 39) that used an auditory-oral educational approach. Age-appropriate scores were observed in 50% of the children on measures of receptive vocabulary, 58% on expressive vocabulary, 46% on verbal intelligence, 47% on receptive language, and 39% on expressive language. Regression analysis indicated that, after controlling for the effects of nonverbal intelligence and parent education level, children who received their implants at young ages had higher scores on all language tests than children who were older at implantation. On average, children with CIs performed better on certain language measures than others, indicating that some areas of language may be more difficult for these children to master than others. Implications for educators of deaf children with CIs are discussed.

Predictors of Reading Skill Development in Children with Early Cochlear Implantation

Objective The present study sought to document the word reading and comprehension levels attained by children who were implanted by 5 yr of age. It was hypothesized that the improved speech perception abilities acquired with cochlear implantation would promote phonological coding skills and facilitate the acquisition of beginning reading skills. Design Three subtests from diagnostic reading assessment batteries standardized on hearing children were administered to 181 children between 8 yr 0 mo and 9 yr 11 mo of age who had 4 to 6 yr of implant experience. In addition, a battery of processing measures was administered including a lexical decision task, a rhyme task and the digit span subtest of the Wechsler Intelligence Scale for Children. Results Over half of the children scored within the average range for their age compared with the normative data for hearing children. Reading competence was associated with higher nonverbal intelligence, higher family socio-economic status, female gender and later onset of deafness (between birth and 36 mo). After variance due to these child and family characteristics was removed, reading competence was associated with mainstream educational placement, use of an updated implant speech processor with a wide dynamic range, and speech processing characteristics that included longer memory span and use of phonological coding strategies. Reading outcome was most highly predicted by linguistic competence and, secondarily, by speech production skill. Conclusion Children who experience severe to profound deafness early in their development have a better prognosis for normal literacy development than ever before. To the extent that use of a cochlear implant is associated with greater use of phonological coding strategies for decoding print, longer working memory spans for short-term storage of phonemes, words and sentences and accelerated language development for reading comprehension, it should have a facilitative effect on the acquisition of literacy.

Long-term outcomes of cochlear implantation in the preschool years: From elementary grades to high school

The objective of this study was to document the development of speech, language, and reading skills between primary and secondary school ages in children who received cochlear implants during preschool years. Subjects were a sample of 85 North American adolescents recruited from a larger sample of 181 participants from a previous investigation. Students were first tested in early elementary school (ages eight to nine years) and were re-evaluated in high school (ages 15–18 years) for this study. The methods used were: performance on a battery of speech perception, language, and reading tests. These were compared at both test ages and significant predictors of outcome level identified through multiple regression analysis. Speech perception scores improved significantly with long-term cochlear implant use. Average language scores improved at a faster than normal rate, but reading scores did not quite keep pace with normal development. Performance in high school was most highly correlated with scores obtained in elementary grades. In addition, better outcomes were associated with lower PTA cochlear implant threshold, younger age at implantation and higher nonverbal IQ. In conclusion, early cochlear implantation had a long-term positive impact on auditory and verbal development, but did not result in age-appropriate reading levels in high school for the majority of students.

Background and educational characteristics of prelingually deaf children implanted by five years of age

Purpose This study documents child, family and educational characteristics of a large representative sample of 8- to 9-yr-old prelingually deaf children who received a cochlear implant by 5 yr of age. Because pre-existing factors such as the child’s gender, family characteristics, additional handicaps, age at onset of deafness and at implant, may affect postimplant outcomes, these variables must be accounted for before the impact of educational factors on performance with an implant can be adequately determined. Classroom variables that may affect postimplant outcomes include placement in public or private, mainstream or special education, oral or total communication environments. Other intervention variables include type and amount of individual therapy, experience of the therapist and parent participation in therapy. Documenting these characteristics for a large representative sample of implanted children can provide clinicians and researchers with insight regarding the types of families who sought early cochlear implantation for their children and the types of educational programs in which they placed their children after implantation. It is important to undertake studies that control for as many of these factors as possible so that the relative benefits of specific educational approaches for helping children to get the most benefit from their cochlear implant can be identified. Method Over a 4-yr period, 181 children from across the US and Canada, accompanied by a parent, attended a cochlear implant research camp. Parents completed questionnaires in which they reported the child’s medical and educational history, characteristics of the family, and their participation in the child’s therapy. The parent listed names and addresses of clinicians who had provided individual speech/language therapy to the child and signed permission for these clinicians to complete questionnaires describing this therapy. Results To the extent that this sample is representative of those families seeking a cochlear implant for their child, especially during the initial period of device availability, this population can be characterized as follows. Most parents had normal hearing, were of majority (white) ethnicity and had more education and higher incomes than the general population. The families tended to be intact with both a mother and a father who involved their hearing-impaired child in family activities on a regular basis. The children were enrolled in the full range of educational placements available across the United States and Canada. Fairly even distributions of children from public and private schools, special education and mainstream classes and oral and total communication methodologies were represented. Educational placement changed as children gained increased experience with a cochlear implant. They received an increased emphasis on speech and auditory skills in their classroom settings and tended to move from private school and special education settings to public school and mainstream programs. These data support the position that early cochlear implantation is a cost effective procedure that allows deaf children to participate in a normal school environment with hearing age mates.

Receptive vocabulary development in deaf children with cochlear implants: Achievement in an intensive auditory-oral educational setting

Objectives: Deaf children with cochlear implants are at a disadvantage in learning vocabulary when compared with hearing peers. Past research has reported that children with implants have lower receptive vocabulary scores and less growth over time than hearing children. Research findings are mixed as to the effects of age at implantation on vocabulary skills and development. One goal of the current study is to determine how children with cochlear implants educated in an auditory-oral environment compared with their hearing peers on a receptive vocabulary measure in overall achievement and growth rates. This study will also investigate the effects of age at implant on vocabulary abilities and growth rates. We expect that the children with implants will have smaller vocabularies than their hearing peers but will achieve similar rates of growth as their implant experience increases. We also expect that children who receive their implants at young ages will have better overall vocabulary and higher growth rates than older-at-implant children. Design: Repeated assessments using the Peabody Picture Vocabulary Test were given to 65 deaf children with cochlear implants who used oral communication, who were implanted under the age of 5 yr, and who attended an intensive auditory-oral education program. Multilevel modeling was used to describe overall abilities and rates of receptive vocabulary growth over time. Results: On average, the deaf children with cochlear implants had lower vocabulary scores than their hearing peers. However, the deaf children demonstrated substantial vocabulary growth, making more than 1 yr’s worth of progress in a year. This finding contrasts with those of previous studies of children with implants, which found lower growth rates. A negative quadratic trend indicated that growth decelerated with time. Age at implantation significantly affected linear and quadratic growth. Younger-at-implant children had steeper growth rates but more tapering off with time than children implanted later in life. Conclusions: Growth curves indicate that children who are implanted by the age of 2 yr can achieve receptive vocabulary skills within the average range for hearing children.

Some Measures of Verbal and Spatial Working Memory in Eight- and Nine-Year-Old Hearing-Impaired Children with Cochlear Implants

Objective The purpose of this study was to examine working memory for sequences of auditory and visual stimuli in prelingually deafened pediatric cochlear implant users with at least 4 yr of device experience. Design Two groups of 8- and 9-yr-old children, 45 normal-hearing and 45 hearing-impaired users of cochlear implants, completed a novel working memory task requiring memory for sequences of either visual-spatial cues or visual-spatial cues paired with auditory signals. In each sequence, colored response buttons were illuminated either with or without simultaneous auditory presentation of verbal labels (color-names or digit-names). The child was required to reproduce each sequence by pressing the appropriate buttons on the response box. Sequence length was varied and a measure of memory span corresponding to the longest list length correctly reproduced under each set of presentation conditions was recorded. Additional children completed a modified task that eliminated the visual-spatial light cues but that still required reproduction of auditory color-name sequences using the same response box. Data from 37 pediatric cochlear implant users were collected using this modified task. Results The cochlear implant group obtained shorter span scores on average than the normal-hearing group, regardless of presentation format. The normal-hearing children also demonstrated a larger “redundancy gain” than children in the cochlear implant group—that is, the normal-hearing group displayed better memory for auditory-plus-lights sequences than for the lights-only sequences. Although the children with cochlear implants did not use the auditory signals as effectively as normal-hearing children when visual-spatial cues were also available, their performance on the modified memory task using only auditory cues showed that some of the children were capable of encoding auditory-only sequences at a level comparable with normal-hearing children. Conclusions The finding of smaller redundancy gains from the addition of auditory cues to visual-spatial sequences in the cochlear implant group as compared with the normal-hearing group demonstrates differences in encoding or rehearsal strategies between these two groups of children. Differences in memory span between the two groups even on a visual-spatial memory task suggests that atypical working memory development irrespective of input modality may be present in this clinical population.

Factors influencing spoken language outcomes in children following early cochlear implantation.

Development of spoken language is an objective of virtually all English-based educational programs for children who are deaf or hard of hearing. The primary goal of pediatric cochlear implantation is to provide critical speech information to the childs auditory system and brain to maximize the chances of developing spoken language. Cochlear implants have the potential to accomplish for profoundly deaf children what the electronic hearing aid made possible for hard of hearing children more than 50 years ago. Though the cochlear implant does not allow for hearing of the same quality as that experienced by persons without a hearing loss, it nonetheless has revolutionized the experience of spoken language acquisition for deaf children. However, the variability in performance remains quite high, with limited explanation as to the reasons for good and poor outcomes. Evaluating the success of cochlear implantation requires careful consideration of intervening variables, the characteristics of which are changing with advances in technology and clinical practice. Improvement in speech coding strategies, implantation at younger ages and in children with greater preimplant residual hearing, and rehabilitation focused on speech and auditory skill development are leading to a larger proportion of children approaching spoken language levels of hearing age-mates.

Measures of digit span and verbal rehearsal speed in deaf children after more than 10 years of cochlear implantation.

Objectives: Conventional assessments of outcomes in deaf children with cochlear implants (CIs) have focused primarily on endpoint or product measures of speech and language. Little attention has been devoted to understanding the basic underlying core neurocognitive factors involved in the development and processing of speech and language. In this study, we examined the development of factors related to the quality of phonological information in immediate verbal memory, including immediate memory capacity and verbal rehearsal speed, in a sample of deaf children after >10 yrs of CI use and assessed the correlations between these two process measures and a set of speech and language outcomes. Design: Of an initial sample of 180 prelingually deaf children with CIs assessed at ages 8 to 9 yrs after 3 to 7 yrs of CI use, 112 returned for testing again in adolescence after 10 more years of CI experience. In addition to completing a battery of conventional speech and language outcome measures, subjects were administered the Wechsler Intelligence Scale for Children-III Digit Span subtest to measure immediate verbal memory capacity. Sentence durations obtained from the McGarr speech intelligibility test were used as a measure of verbal rehearsal speed. Results: Relative to norms for normal-hearing children, Digit Span scores were well below average for children with CIs at both elementary and high school ages. Improvement was observed over the 8-yr period in the mean longest digit span forward score but not in the mean longest digit span backward score. Longest digit span forward scores at ages 8 to 9 yrs were significantly correlated with all speech and language outcomes in adolescence, but backward digit spans correlated significantly only with measures of higher-order language functioning over that time period. While verbal rehearsal speed increased for almost all subjects between elementary grades and high school, it was still slower than the rehearsal speed obtained from a control group of normal-hearing adolescents. Verbal rehearsal speed at ages 8 to 9 yrs was also found to be strongly correlated with speech and language outcomes and Digit Span scores in adolescence. Conclusions: Despite improvement after 8 additional years of CI use, measures of immediate verbal memory capacity and verbal rehearsal speed, which reflect core fundamental information processing skills associated with representational efficiency and information processing capacity, continue to be delayed in children with CIs relative to NH peers. Furthermore, immediate verbal memory capacity and verbal rehearsal speed at 8 to 9 yrs of age were both found to predict speech and language outcomes in adolescence, demonstrating the important contribution of these processing measures for speech-language development in children with CIs. Understanding the relations between these core underlying processes and speech-language outcomes in children with CIs may help researchers to develop new approaches to intervention and treatment of deaf children who perform poorly with their CIs. Moreover, this knowledge could be used for early identification of deaf children who may be at high risk for poor speech and language outcomes after cochlear implantation as well as for the development of novel targeted interventions that focus selectively on these core elementary information processing variables.