Increasing numbers of infants and young children are now presenting to implantation centers and early intervention programs as the impact of universal newborn hearing screening programs is felt worldwide. Although results of a number of studies have highlighted the benefit of early identification and early fitting of hearing devices, there is relatively little research on the impact of early fitting of these devices on first language milestones. The aim of this study was to investigate the early spoken language milestones of young children with hearing loss (HL) from two perspectives: first, the acquisition of the first lexicon (i.e., the first 100 words) and second, the emergence of the first word combinations.
Two groups of participants, one comprising 24 participants with profound HL and a second comprising 16 participants with normal hearing, were compared. Twenty-three participants in the HL group were fitted with a cochlear implant and one with bilateral hearing aids. All of these were “switched-on” or fitted before 30 months of age and half at <12 months of age. Language data were collected using the Diary of Early Language, a procedure in which parents recorded their child's first 100 spoken single words and any word combinations produced while reaching this single-word target. Acquisition of single words was compared by using the time period (in days) taken to reach several single-word targets (e.g., 50 words, 100 words) from the date of production of the first word. The emergence of word combinations was analyzed from two perspectives: first, the time (in days) from the date of production of the first word to the emergence of the first word combinations and second, the size of the single-word lexicon when word combinations emerged.
The normal-hearing group required a significantly shorter time period to acquire the first 50 (mean <1.9 months) and the first 100 (mean <3.9 months) words than the HL group. Although both groups demonstrated acceleration in lexical acquisition, the hearing group took significantly fewer days to reach the second 50 words relative to the first 50 words than did the HL group. Finally, the hearing group produced word combinations significantly earlier (i.e., in fewer days from production of the first word) than the HL group; however, the size of the single-word lexicon when word combinations emerged was similar for both groups.
The results of this study suggest that despite fitting of a device at an early age, HL continues to impact early lexical acquisition and the emergence of word combinations. Further, similarities between the hearing and HL groups, such as the overall pattern of lexical acquisition and a lexicogrammatical link, suggest that the processes underpinning early language acquisition for hearing children and those with HL may also be similar.