Prosodic changes in speech following brain damage: Acoustic and neuroradiographic measures

Abstract

Two prosodic parameters, fundamental frequency (F0) and intensity, along with a measure of vowel duration, were studied in 11 Broca, 7 Wernicke, 15 Parkinson, and 15 normal-control subjects performing four speech tasks: reading, counting, conversation, and vowel prolongation. Tape-recorded speech samples were played into a microprocessor controlled speech analyzer (PM 301 Voice Identification, Inc.), where F0 in Hertz and intensity in relative decibels were calculated. Measures of mean F0 and F0 variability, mean intensity and intensity variability, and duration of the prolonged vowel were analyzed. Values differed across speech tasks: Overall, F0 and intensity values were higher in reading than in the other three tasks. Further, a significant group by task interaction was found for mean F0. Broca and Parkinson patient groups had abnormally high F0 mean values, but differed from each other in F0 variability (Broca having high and Parkinson having low F0 variability) and mean intensity; surprisingly, the Broca group had intensity values significantly lower than the other groups. All three clinical groups differed significantly from normals on the duration measure. Examination of PET and CT-scan data in individual patients indicated an association between prosodic impairments and specific frontosubcortical dysfunction, areas subserving motor abilities in speech production.