Assessing Higher Order Language Processing in Long-Term Cochlear Implant Users

Purpose The purpose of this study was to describe and explain individual differences in complex/higher order language processing in long-term cochlear implant (CI) users relative to normal-hearing (NH) peers. Method Measures of complex/higher order language processing indexed by the Clinical Evaluation of Language Fundamentals-Fourth Edition (CELF-4) Core Language subtests were obtained from 53 long-term (≥ 7 years) CI users aged 9-29 years and 60 NH controls who did not differ in age, gender, or nonverbal IQ. Vocabulary knowledge and fast, automatic language processing (rapid phonological coding, verbal rehearsal speed, and speech intelligibility) were also assessed. Results CI users showed weaker performance than NH controls on all CELF-4 Core Language subtests. These differences remained for Formulated Sentences and Recalling Sentences even when vocabulary knowledge was statistically controlled. About 50% of the CI sample scored within the range of the NH sample on Formulated Sentences and Recalling Sentences, while the remaining 50% scored well below the NH sample on these subtests. Vocabulary knowledge, rapid phonological coding, verbal rehearsal speed, and speech intelligibility were more strongly correlated with CELF-4 subtest scores in the CI sample than in the NH sample. Conclusions Weaknesses in complex, higher order language processing shown by a subgroup of CI users compared to NH peers may result from delays in fast, automatic processing of language. These at-risk domains of language functioning could serve as targets for novel interventions for deaf children who experience suboptimal spoken language outcomes following cochlear implantation.