This paper attempts to make certain qualitative differences between stutterers and non-stutterers clear by means of acoustic analysis. Previous studies have highlighted three areas of relevance to this study. The first is that breath control while speaking is difficult for stutterers. Secondly, the beginning of words are particularly challenging for stutterers. Finally, even without treatment, stutterers have on average an 80% chance of naturally recovering. The author collected data from 61 stutterers and the same number of non-stutterers, by recording their voices and analyzing them acoustically, such as for shimmer parameters. The conclusions are as follows. Preschool children (two to six years) and adults (twenty years or above) who stutter registered a statistically significant increase in score for Amplitude Perturbation Quotient (APQ) and Shimmer Parameter (SP) than non-stutterers of the same age range. This data suggests that stutterers have something wrong with their respiratory controls. On the other hand, for children of 7〜9 years old, APQ and SP scores were not statistically different between stutterers and non-stutterers. This suggests that the second stage of laryngeal development is correlated to the process of natural recovery. Also stutterers' problem of disfluency would appear to originate in the motor speech center in the brain.

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The present study attempts to reexamine what is oft-times referred to as "Natural Process Analysis (NPA)" from a phonological and clinical perspective. First, theoretical implications of NPA are examined. Based upon modern phonology, an analytic tool should necessarily be equipped with theoretical constructs including input and output forms, and intervening rules, processes, or constraints, depending upon the framework. NPA fails because it only relies upon dynamic processes to reach output forms, always positing adult-like input forms for each and every child. Second, for NPA, phonemes are the smallest phonological unit to be analyzed. This assumption sometimes leads to correct output forms resulting from incorrect input forms because it fails to take distinctive features into account. Finally, it is suggested that practical clinicians be provided with a proper knowledge of phonology to conduct a clinically effective phonological analysis of functional misarticulation systems.

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To elucidate the neural basis of stuttering, brain activation for reading words was compared between adults who do and do not stutter (AWS/ANS) with functional MRI. Japanese native speakers read aloud familiar (F), unfamiliar (U) and pseudo- (P) words of 4 or 5 syllables. P contained much fewer native syllable sequences than F or U. F primarily activated the left angular/supramarginal gyri (lAG/SMG), U Broca's area, and P the left ventral premotor/motor areas (lvPMA/MA), respectively, in ANS. AWS showed lower activation in lAG/SMG and Broca's area, but higher activation in lvPMA/MA, implying that AWS cannot read native syllable sequences as efficiently as ANS.

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This research is focused on the implementation of direct speech therapy for school age children who developed stuttering. Two subjects were examined the effective treatment method that considered both environmental modification and counseling approach. In direct speech therapy, they were taught the method of speaking slowly in gentle voice onset and prolonged speech using a gentle voice. And the therapy was focused on the speech sound with high stuttering frequency and difficulty. Through the treatment, both subjects showed improvement in fluency and severity of stuttering as well as behavioral and psychological aspects.

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[in Japanese]

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This study compared the disfluencies of Japanese-speaking 24 preschool children who stutter (CWS) with those produced by age- and sex-matched comparison 24 children who do not stutter (CWNS). Part-word repetitions, prolongations and blocks were significantly more frequent in CWS than in CWNS, whereas no significant group differences occurred with respect to single-syllable word repetitions. Although a cut-off of 3 stuttering-like disfluencies (SLD) per 100 morae could classify only 46% of the CWS, 1 SLD per 100 morae could classify 96% of them. Our data showed single-syllable word repetitions are not the SLD and 1 SLD per 100 morae is an appropriate cut-off point in Japanese.

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[in Japanese]

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