乳兒期初期の音聲發達

Abstract

The purpose of this paper is to throw light on the mechanism of developmental process of speech in early infancy (until imitative sounds and meaningful words appear) as the contribution to the foundation for the development of language. For this purpose, based on several literatures and the results on the writer's own observations of infants behavior and records of their voice, the factors determining developmental process of speech and the other problems in this period were discussed. The discussion is summarized as follows: 1) As to the question which of the two kinds of vocalization, crying and non-crying, develops into human language, it was indicated that crying can be only a basis of communication on the animal level, while non-crying and meaningless utterances is important basis for real human language as the system of symbols. 2) It was found, concerning these non-crying utterances, from 2 to 10 months of age, their functional meaning as well as vocal sounds was changing gradually. Earlier utterances expressive of comfortable state deve lop to have functional significance as means for strengthening an infant's emotional attachment to his mother in playing with her, or as means for playing by himself, and it seems to the writer that these provide the foundation for the formation of imitative or meaningful words. 3) As for Mowrer's autism theory about language learning, however it is suggestive, the writer obtained the data inconsistent with some points of his theory. 4) Comparing the process of speech development of an infant born deaf with those of normal ones, it was found that the process of babbling formation is determined by interaction between maturational factors and learning factors. Learning factors, including for an infant to hear his mother's voice and to rehearse and practise his own voice, differ in their effects according to maturational stage, and that maturational factors, in turn, function only when related to learning factors.