Why are some deaf children very successful with their CIs, often achieving “near-normal” scores within the range of variation observed in typically developing age-matched normal-hearing (NH) peers, while other children struggle and show substantial delays and weaknesses in domains, such as speech perception, spoken word recognition, sentence processing, vocabulary, language, and reading? Answers to these questions about the underlying factors that are responsible for the variability in speech and language outcomes after implantation have important clinical implications for improving diagnosis, treatment, and management of children with profound hearing loss. One of our long-term objectives is to understand and explain the enormous variability and individual differences in speech and language outcomes in deaf children who have received cochlear implants (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. 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. 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. Conclusions:ĭespite 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. 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. 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. 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. 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. 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. Sentence durations obtained from the McGarr speech intelligibility test were used as a measure of verbal rehearsal speed. 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. 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 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. Little attention has been devoted to understanding the basic underlying core neurocognitive factors involved in the development and processing of speech and language. Conventional assessments of outcomes in deaf children with cochlear implants (CIs) have focused primarily on endpoint or product measures of speech and language.
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