Basis of intonation disturbance in aphasia: Perception

This study sought to determine whether abnormalities exhibited by patients with aphasia in intonation reception are attributable to deficit in processing (1) global (overall) pitch or fundamental frequency (F0) contours, or (2) components of F0 contours. Two experiments involving identification of matched statements and echo questions were conducted. The stimuli in Experiment 1 were full sentences (Global F0 condition), whereas those in Experiment 2 were sentences split into two parts (Partial F0 condition). Patients with fluent aphasia performed comparably with non-brain damaged control subjects on the identification of both stimulus types in both experiments. Patients with mild to moderate nonfluent aphasia performed similarly on the identification of statements, but they were impaired on the identification of questions. In Experiment 2, they performed comparably with control subjects on the identification of one part of the split question stimuli, but not the other part. Severely impaired nonfluent patients participated in Experiment 1 only, and they performed poorly on the identification of both stimulus types. Taken together, these findings suggest that intonation might be processed in units smaller than global F0 information, and that impaired ability to process those units might in part explain the nature of intonation disturbance in aphasia.