Abstract
The purpose of this study was to clarify differences in speech sound errors among Broca's aphasics, conduction aphasics and Wernicke's aphasics. While this issue has been analyzed in former researches within single modalities (confrontation naming and/or repetition) separately, the present study focused on similarity of error patterns observed across various speech modalities : confrontation naming, repetition, and reading aloud of Kanji and Kana words. The subjects were four Broca's aphasics, three conduction aphasics and five Wernicke's aphasics. 60 words ranging from three to five syllables were used. Consonant errors were analyzed and classified into five categories : substitution, transposition, omission, addition and distortion. The results indicated the following.
1) In conduction aphasics and Wernicke's aphasics, substitution and transposition accounted for almost 90% of the errors observed. The rates of these two error patterns varied for each case. In the Broca's aphasics, error categories which took the largest rates varied from case to case.
2) Relatively similar error patterns were observed across all four speech modalities in the Broca' s aphasics and conduction aphasics. On the other hand, in Wernicke's aphasics error patterns were varied over different speech modalities. These findings suggest that :
1) In classifying speech sound errors according to types of aphasia, it is beneficial to focus on similarity of error patterns across four speech modalities rather than to compare error patterns within each modality respectively.
2) With regard to Broca's aphasics and conduction aphsics, speech sound errors in the four speech modalities are caused by the same mechanism for each aphasic type, since common error patterns are observed throughout all speech modalities. On the other hand, speech sound errors in Wernicke's aphasics seemed to be caused by several factors.
