Use of the analysis by synthesis model of speech perception by children acquiring the sound system of language

During the time when a child learns the sound system of his language, there is much evidence that the child can perceive phonological distinctions and therefore detect phonetic differences before he can produce these distinctions. This evidence is often provided to disprove the hypothesis that the child could be using an "active" model of speech perception. One such model, the analysis by synthesis model of speech perception, supposes that decoding of the acoustic signal employs the articulatory representation that would be required to produce the hypothesized identity of the incoming signal. The model proposes that while the human auditory system is innately equipped to handle the segments contained in speech, that the correlations between the acoustic information and articulation are learned with experience and form the basis for the division of the continuous acoustic signal into discrete categories of speech sounds. This thesis reviews recent research into the speech perception process and revises the analysis by synthesis model. It reveals that the human auditory system is innately equipped to divide stimuli (both speech and non-speech) that vary along certain acoustic dimensions into discrete classes. The unique processing that results for speech stimuli, occurs when the stimuli is recognized as having a function in the system of language. Hence the requirements for phonetic processing involve the psychological realization that stimulus originated in the human vocal tract. This investigation then reviewed the available literature on the perception and production of children acquiring language to determine whether there is support for their use of the revised analysis by synthesis model. The results favoured that children do use such a model. When resolving the various acoustic cues that combine to form a stimulus complex, the child does refer to his articulatory abilities. Lacking full articulatory knowledge, the perceptual errors that typify children's language, occur. It was shown that the child need not have the precise adult articulatory configuration in order to utilize this model. The model is operative during the child's perception of both himself and the adult. In both instances the comparator performs the function of matching the child's articulatory representation with his perceived representation of a form. The results serve to improve his knowledge of acoustic-articulatory correlations. In this manner the processes of perception and production are closely integrated and as understanding of their fine interrelationship improves, production becomes more accurate and perception is simplified.Medicine, Faculty ofAudiology and Speech Sciences, School ofGraduat