Vowel production in aphasia

Abstract

A group of five anterior and seven posterior aphasic patients were recorded for their vowel productions of the nine nondipthongized vowels of American English [Peterson and Barney, J. Acoust. Soc. Am. 24, 175–184 (1952)], and compared to the productions of a group of seven normal speakers. All phonemic substitutions were eliminated from the data base. A linear predictive coding program was used to extract the first and second formant frequencies for each of the five repetitions of the nine vowels. The vowel duration and the fundamental frequency of phonation were also measured. Statistical analyses revealed that the duration and the fundamental frequency for the aphasics were significantly different from the normal subjects. Although there were no significant differences in the formant frequency means, there were significantly larger standard deviations for the aphasic group. This greater variability was considered as evidence of a phonetic deficit on the part of the aphasic speakers, in the context of preserved phonemic organization. [Work supported by ADAMHA.]