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.