Early Language Development in Children with Profound Hearing Loss Fitted with a Device at a Young Age: Part II—Content of the First Lexicon

Abstract

Lexical content is commonly understood to refer to the various categories of words that children produce and has been studied extensively in children with normal hearing. Unlike the hearing child, however, little is known about the word categories that make up the first lexicon of children with hearing loss (HL). Knowledge of the first lexicon is increasingly important, as infants with HL are now being detected through universal newborn hearing screening programs and fitted with hearing aids and cochlear implants in before 12 months of age. For these children, emergence of the first spoken words is a major milestone eagerly awaited by parents and one of the first verbal language goals of teachers and therapists working with such children. The purpose of this study was to evaluate the lexical content of the first 50 and 100 words produced by children with HL and to contrast this with that of a group of hearing children. Lexical content was compared in two groups of children: one group composed of 24 participants with severe profound or profound HL and a second group composed of 16 participants with normal hearing. Twenty-three participants in the HL group were fitted with a cochlear implant and one with bilateral hearing aids. All were "switched on" or fitted before 30 months of age. The Diary of Early Language (Di-EL) was used to collect a 100-word lexicon from each participant. All single word and frozen phrase data from each child's Di-EL were allocated to 1 of 15 word types grouped into four word categories (noun, predicate, grammatical, and paralexical), and the results were compared for both groups. The hearing and HL groups showed similar distributions of word categories, with nouns constituting the largest portion of the lexicon followed by predicates and paralexicals. Grammaticals made up the smallest portion of the lexicon. However, several significant differences were evident between the two groups. In both the 50- and 100-word lexicons, the hearing group used proportionately more nouns, fewer predicates, more common nouns, and fewer onomatopoeic words compared with the HL group. Further, more participants in the hearing group used grammatical word types other than adverbs (including pronouns) compared with the HL group. Overall, lexical content of the HL group was similar to that of the hearing group for both the 50- and 100-word lexicons, although some differences in proportional use were noted across word categories and types. It is suggested that differences in the quantity and diversity of language experienced by children with normal hearing compared with those with HL, together with differences in the input they receive, might in part explain these differences. The effect of quality of speech input and therapy method on the emerging lexicon and subsequent language development will be particularly important in informing appropriate intervention strategies for children with HL.