[The effects of early manual instruction on the oral language development of two deaf children]

The speech and language training for deaf children at our clinic is performed using a multisensory method, which consists of reception and expression training for sign language and fingerspelling as well as auditory training, lip reading, and written language training (the Kanazawa Method). We have already reported that acquisition of written language is not dependent on oral language, and that written language is easier to learn than oral language for deaf children. In the present investigation, we analyzed the acquisition of comprehensible and expressive vocabulary in sign language and fingerspelling. The subjects were two children congenitally deaf at levels higher than 105dB. Recorded language samples by the age of 48 months were analyzed. Acquisition of sign language was found to be significantly easier than acquisition of oral language. The development of expressive noun words, function words, and Wh-question words in sign language at the early period was almost equivalent to that of hearing peers, and then the sign language appeared transfer to the oral language. These results suggest that early presentation of sign language with written and oral language is effective in the acquisition of communicative attitudes, function words and interrogative sentences which are most difficult for the hearing-impaired. It was shown that early presentation of sign language with written and oral language serves to promote acquisition of oral language.