中枢性言語障害をもつ幼児の音声発達

Abstract

In previous papers the writer (7, 9, 10) reported on the speech development of normal infants and that of an infant suffering from a hearing disorder. This paper reports on observations made of a girl suffering from a central language disorder, who was studied longitudinally from birth to 4 years of age so as to secure more information on related problems of speech development. The observations and interpretations are summarized below. Observations As shown in Figure I., the behavioral development of this child is nearly normal in motor, adaptive and communicative areas of behaviour until approximately no years and 8 months (0 ; 8), except that consonant patterns in babbling did not appear. From about 1 ; 0 however, the retardation of her behavioral development became remarkable. Also, a regression pattern was observed in which sounds once uttered disappeared. Examples of such regression include imitative sounds from 1 ; 6 to 1 ; 7 and consonant patterns in babbling from 1 ; 6 to 3 ; 0. For the most part, her utterances were repetitions of stereotyped vowel-like sounds. She uttered these sounds more frequently when playing alone or by her mother's side, though not playing with her mother at the time. She could not imitate sounds uttered by her mother or others even though they tried to approximate sounds in her repertoire. Figure II. shows some interesting problems in speech development if comparisons are made among the observations made of a normal child, of a child suffering from a hearing disorder and of this child. Especially interesting, in comparing the non-crying utterances of this child to those of a child suffering from a hearing disorder, is that the frequency of the former seems to indicate she can respond to sounds apart from understanding their meanings. In spite of her abundant utterrnces she was not observed to have any higher communicative functions and did not seem to need a more complex level of communication. Her only communicative sounds were those used in crying, which was used for communicating her basic needs to others. As for her physically and psychologically idiosyncratic syndromes, the former consisted of a weak and allergic constitution and the latter of overcleanliness, stereotyped behavior patterns, unfixed eyes, egocentricity in human relations and difficulty in controlling the framework of behavior. Interpretations Some of her idiosyncratic syndromes coincide with those counted among characteristics of infantile autism by Kanner, L., (2, 3). However, she showed no tendency to be "happiest when left alone" which is a basic syndrome of infantile autism. She did not like to be left alone in the obrervation room and ran after her mother. She was egocentric and yet dependent. Their character shows that she was not a typical case of infantile autism, and it is presumed that she had a kind of autistic tendency as egocentric and dependent tendencies resulting from her delicate body, nervousness, central language disorder, and several environmental factors. The lack of variety and flexibility in her utterances suggests that language control from higher levels of the central nervous system is very important to the differential development of babbling. Such an interpretation would support Mc-Carthy's hypothesis that "Vowel development seems to be analogue to gross motor development and consonant development to the individuation of specific finer movements essential for the pronunciation of real words... The emergence of a variety of consonant sounds... marks the beginning of cortical control of speech." As Figure II. shows, normality of both the control function and the hearing function of the central nervous system is necessary for speech development. This is so even for meaningless utterances, and in normal children the variety, flexibility and abundance of their utterances is determined by interaction of the two functions. The writer assumed that not only differentiation of personality but also differentiation of autistic and social babbling during 0 ; 6 through 0 ; 10 are found associated in the developmental process, and furthermore the interaction of these differentiating functions promote differentiations in adaptive growth. This assumption is applied to this child in inverse form, because undifferentiation of babbling and personality mutually restrains their differenciation from the viewpoint of the above assumption