Voice onset time perception in aphasic subjects.

概要

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To obtain accurate information on auditory perceptual deficits of aphasia, the present study examined the identification of synthetic sounds (both speech and non-speech) with varying voice onset times (VDTs) in normal (both young adult and aged) and aphasic subjects. Major findings included the following : (1) the data from an identification experiment with non-speech stimuli obtained only from the normal young adult subjects showed evidence for the existence of categorical judgment for such stimuli ; (2) There is no difference in the values of μ (the category boundary), σ (the accuracy of identification) and qe (the category confusion rate) between the normal young adult and aged subjects, suggesting that aging does not seem to affect the VOT perception of speech stimuli ; (3) approximately two thirds of the aphasic subjects exhibited abnormal values of μ, σ or qe, indicatting that they had problems in the VOT perception of speech stimuli. A further analysis suggests that the problems of the majority of these subjects may be attributable not only to difficulty in identifying (labeling) the stimuli but also to difficulty in processing the acoustic and/or phonetic information of the stimuli.