The effect of hearing loss on the use of lexical categories by Hebrew-speaking mothers of deaf children with cochlear implants

Background and objectives: The frequency of use of nouns versus verbs in child-directed speech (CDS) of mothers to their normal hearing (NH) children has been investigated in various languages. Recent studies have shown that CDS to deaf children is affected by hearing loss. Thus, the main aim of the present study was to examine the effect of hearing loss on the use of content words by NH Hebrew-speaking mothers to their deaf children using CIs. The second aim was to compare the use of content words by mothers speaking to CI children to that of NH children of the same chronological age and NH children with the same hearing experience.

Method: Three groups of mother-child dyads participated: Ten mothers of deaf children with bilateral CIs (CIs) (age range 20-48 months), ten mothers of NH children matched to the deaf children by their chronological age (NCA), and ten mothers of NH children matched to the deaf children by their hearing experience (NHE). Data were collected from mother-child dyads performing natural activities. Two hundred utterances were transcribed and analyzed both quantitatively (tokens) and qualitatively (types) according to the use of lexical categories (noun, verb, adjective, and adverb).

Results: The frequency of verbs and nouns, both types and tokens, was significantly higher than the frequency of adverbs and adjectives in the CDS of mothers to their children both with CIs and NH. No significant differences were found between the use of verb and noun tokens by mothers of children with NH in both groups. However, in the speech of mothers to the CI group, the use of verb tokens was significantly higher than the use of noun tokens, and the verb to noun ratio of tokens was significantly higher than that of the NHE group, and demonstrated a trend with the NCA group.

Conclusion: The fact that mothers of CI children use more verb than noun tokens strengthens the claim that they adopt a more directive style and controlling behaviors while interacting with their CI children. Also, it seems that mothers speaking to CI children are more sensitive to the children's linguistic needs according to the hearing experience and linguistic stage rather than the chronological age. The clinical implications are discussed.