DURATIONAL FACTORS IN THE PHONETIC PERCEPTION OF APHASICS.
Item
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Title
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DURATIONAL FACTORS IN THE PHONETIC PERCEPTION OF APHASICS.
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Identifier
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AAI8222973
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identifier
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8222973
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Creator
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RIEDEL, KAREN LOUISE.
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Contributor
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Michael Studdert-Kennedy
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Date
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1982
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Language
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English
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Publisher
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City University of New York.
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Subject
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Language, Linguistics
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Abstract
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This study used synthetic speech and sine-wave control stimuli to investigate aphasics' ability to identify and discriminate speech and nonspeech distinctions conveyed by acoustic duration. The results revealed no evidence to support the claim that the primary deficit underlying aphasics' difficulty in understanding spoken language is a failure to extract relevant acoustic information from rapid changes in the speech signal. Rather, findings indicated that aphasics with marked impairment in spoken language comprehension were able to discriminate brief formant transitions which accompany changes in the place of articulation and no consistent improvement in phonological performance was obtained when these spectral changes occurred more slowly. Aphasic subjects also demonstrated sensitivity to manipulations in syllable duration which are known to result in a shift in the phonetic perception of normal listeners. Specifically, aphasic subjects showed a displacement of the category boundary or peak of discrimination dependent on syllable duration for synthetic speech continua appropriate for a contrast in manner /b-w/ or voicing /d-t/. In addition, aphasics' perception of voicing of the final stop consonant in a CVC syllable was affected by a variation in the duration of the syllable-initial formant transitions to the same degree as was found in normal listeners. Since for both populations, the effects produced by durational manipulations were confined to synthetic speech stimuli, results support the notion that speech processing engages a special set of perceptual mechanisms different from those which govern the perception of nonspeech auditory signals.;Although even aphasics with rather severe comprehension deficits were able to discriminate small changes in acoustic duration, they manifested selective difficulty identifying test stimuli reliably. The failure to maintain consistent category judgments was not specific to fluent or nonfluent aphasics, but was specific to aphasics manifesting reduced Token Test scores, and as a group, overall phonological task performance was highly correlated with Token Test score. These findings suggest that the performance deficit found in some aphasics is not a failure to perceive small changes in the acoustic signal, but a general inability to assign a category label to the stimulus.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
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Program
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Speech and Hearing Science
