Phonological factors in auditory comprehension in aphasia

Abstract

It was the object of this study to investigate whether the comprehension deficit of Wernicke aphasics can be attributable to a selective deficit in phonemic hearing or phonemic discrimination as suggested by Luria. The ability to make phonemic discriminations between real words and nonsense syllables in relation to level of auditory comprehension was compared in 25 aphasic patients: 6 Broca's, 6 Mixed Anteriors, 6 Wernicke's, and 7 unclassified Posterior aphasics. The aphasics' ability to discriminate other phonological contrasts such as syllable structure and phoneme order was also tested. The subject's task was to indicate if two auditorily presented stimuli were the same or different. Results indicated that Mixed Anterior aphasics, who had only moderate comprehension deficits, performed worse on all phonological discriminations. Wernicke aphasics, with much more severe comprehension deficit, were less impaired in the present task. However, only the posterior aphasics (including Wernickes) had more difficulty in discriminating place of articulation than voicing contrasts. This deficit was interpreted as reflecting an impairment in linguistic encoding of speech sounds in the auditory association areas. It was concluded that a deficit in phonemic hearing cannot account for the comprehension deficit of Wernicke's aphasics.