Early prelingual auditory development and speech perception at 1-year follow-up in Mandarin-speaking children after cochlear implantation
The primary purpose of the current study was to evaluate early prelingual auditory development (EPLAD) and early speech perception longitudinally over the first year after cochlear implantation in Mandarin-speaking pediatric cochlear implant (CI) recipients. Outcome measures were designed to allow comparisons of outcomes with those of English-speaking pediatric CI recipients reported in previous research. A hierarchical outcome assessment battery designed to measure EPLAD and early speech perception was used to evaluate 39 pediatric CI recipients implanted between the ages of 1 and 6 years at baseline and 3, 6, and 12 months after implantation. The battery consists of the Mandarin Infant-Toddler Meaningful Auditory Integration Scale (ITMAIS), the Mandarin Early Speech Perception (MESP) test, and the Mandarin Pediatric Speech Intelligibility (MPSI) test. The effects of age at implantation, duration of pre-implant hearing aid use, and Mandarin dialect exposure on performance were evaluated. EPLAD results were compared with the normal developmental trajectory and with results for English-speaking pediatric CI recipients. MESP and MPSI measures of early speech perception were compared with results for English-speaking recipients obtained with comparable measures. EPLAD, as measured with the ITMAIS/MAIS, was comparable in Mandarin- and English-speaking pediatric CI recipients. Both groups exceeded the normal developmental trajectory when hearing age in CI recipients and chronological age in normal were equated. Evidence of significant EPLAD during pre-implant hearing aid use was observed; although at a more gradual rate than after implantation. Early development of speech perception, as measures with the MESP and MPSI tests, was also comparable for Mandarin- and English-speaking CI recipients throughout the first 12 months after implantation. Both Mandarin dialect exposure and the duration of pre-implant hearing aid use significantly affected measures of early speech perception during this time period. EPLAD and early speech perception exhibited similar patterns of improvement during the first 12 months after early cochlear implantation. The duration of pre-implant hearing aid use had a significant positive effect on both categories of outcome measures. Consistent post-implant EPLAD trajectories and early speech perception results provide objective evidence that can guide best practices in early intervention protocols.