LEXICAL growth, grammatical competence and discourse reference: potential risks for children with a hearing deficiency *

This paper compares the morpho-syntactic development for two Dutch children, a normal hearing child and a child that suffered from repeated otitis media between of 2 and 31⁄2 years. A temporary hearing deficiency causes a leveling and distortion of phonetic processes, and a delay in lexical growth. When such a deficiency occurs during the sensitive period, it results in a temporary stagnation of the morpho-syntactic development. This stagnation showed off dramatically when the longitudinal graphs of finite verb acquisition and determiner acquisition were constructed for this particular case. Both the acquisition of finite verbs and the acquisition of determiners took twice as long for the child with otitis media. The stagnation period showed up for the period of the ear infections. The child’s delay in grammatical orientation affects the acquisition of discourse coherence and reference tracking. A system equipped with finite verbs and determiners allows the attention to be directed at specific points. As such, it delivers a powerful tool for the further extension and the maintenance of the lexicon (Van Kampen 2001, 2005). From here on, one may take an optimistic or a pessimistic view. The optimistic view is that the acquisition devices are sufficiently elastic to overcome a delay in lexical growth. The pessimistic view is that the delayed lexical growth may prevent a clear shift to a grammatical orientation, as argued in Locke (1997) and may fail to yield the further enhancement of the lexicon. In that case, a temporary hearing deficiency may cause a delay in lexical growth that results in a far longer lasting effect in grammatical competence. A long-term objective of acquisition studies must be to explore the elasticity of language acquisition in these qualitative terms. 1. Normal language acquisition Language acquisition is a step-wise process. Some features of the mother language are acquired earlier than others. Productive child language starts with a radical and systematic reduction of the maternal input. Grammatical markings and words are mainly left out. The first utterances of the child consist of names and single words. In a next step, the child simplifies the input to (mainly) binary combinations of words with denotational content {e.g. bear sweet/bear sleep} and operator-like words with immediate situational deixis {e.g. that bear}. The combinatorial use of words enhances the opportunities to acquire new words. The number of words productively used within the binary constructions rises to something between 300 and 500 (first ‘lexical spurt’) (Bates, Dale & Thal 1995).