Speech production mechanisms in aphasia: A delayed auditory feedback study

Results indicated that only the category of vowel length produced a significant number of errors, suggesting that DAF affects articulatory implementation, and support Wernicke's and Geschwind's model, in which Conduction aphasics have a disconnection between the sensory and motor images of words.

Abstract

Data collected from a delayed auditory feedback (DAF) study conducted by F. Boller, P. B. Vrtunski, Y. Kim, and J. L. Mack (1978, Cortex, 14, 212–226) were reanalyzed to determine if speech quality measures which were significantly affected during DAF could be operationalized and to ascertain which type of errors are responsible for the judgement. A second goal of this study was to determine if Conduction aphasics were relatively spared under conditions of DAF, as has been shown in previous studies. Twenty aphasic patients and ten controls were presented with several speech production tasks under two delay conditions and two simultaneous feedback conditions. Results indicated that only the category of vowel length produced a significant number of errors, suggesting that DAF affects articulatory implementation. Conduction aphasics showed the least effect of all the groups. These results support Wernicke's and Geschwind's model, in which Conduction aphasics have a disconnection between the sensory and motor images of words. In contrast, Broca's aphasics were the most affected group under DAF, suggesting that a major component of their disorder is phonetic in nature.