Modeling spoken word recognition performance by pediatric cochlear implantusers using feature identification

Objective: Computational simulations were carried out to evaluate the appro priateness of several psycholinguistic theories of spoken word recognition for children who use cochlear implants. These models also investigate the i nterrelations of commonly used measures of closed-set and open-set tests of speech perception. Design: A software simulation of phoneme recognition performance was develo ped that uses feature identification scores as input. Two simulations of le xical access were developed. In one, early phoneme decisions are used in a lexical search to find the best matching candidate. In the second, phoneme decisions are made only when lexical access occurs. Simulated phoneme and w ord identification performance was then applied to behavioral data from the Phonetically Balanced Kindergarten test and Lexical Neighborhood Test of o pen-set word recognition. Simulations of performance were evaluated for chi ldren with prelingual sensorineural hearing loss who use cochlear implants with the MPEAK or SPEAK coding strategies. Results: Open-set word recognition performance can be successfully predicte d using feature identification scores. In addition, we observed no qualitat ive differences in performance between children using MPEAK and SPEAK, sugg esting that both groups of children process spoken words similarly despite differences in input. Word recognition ability was best predicted in the mo del in which phoneme decisions were delayed until lexical access. Conclusions: Closed-set feature identification and open-set word recognitio n focus on different, but related, levels of language processing. Additiona l insight for clinical intervention may be achieved by collecting both type s of data. The most successful model of performance is consistent with curr ent psycholinguistic theories of spoken word recognition. Thus it appears t hat: the cognitive process of spoken word recognition is fundamentally the same for pediatric cochlear implant users and children and adults with norm al hearing.