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INTRODUCTION
Prosody is the collective name given to lawful changes in loudness, pitch, speech rate, rhythm, and melody critical to conveying both linguistic and emotional messages. Traditionally, the left hemisphere has been assigned the major role in controlling linguistic prosody and the right hemisphere in controlling emotional prosody. A disruption of the comprehension or expression of emotional prosody has been called aprosodia (Monrad-Krohn, 1947; Ross, 1981; Myers, 1999). In the most severe cases of receptive aprosodia, a listener may be completely ignorant of a speaker's emotional intent, especially when the propositional verbal message differs from the prosodic emotional message (Bowers et al., 1987; Heilman et al., 1984). In the most severe expressive cases, even strongly emotional content may be conveyed with little variation in intonation, rate, or stress (Tucker et al., 1997). The listener is left to guess about the speaker's emotional investment in the speech content. Expressive aprosodia can result from anterior cortical, posterior cortical, or subcortical lesions (Ross, 1981). Types of aprosodia, mirroring types of aphasia, have been posited (Ross, 1981). The emphasis of the present study is on expressive aprosodia whether or not it is accompanied by receptive deficits.
Despite expressive aprosodia's negative effects on human performance, only limited behavioral treatment data are available. Anderson and colleagues (Anderson et al., 1999) employed a single subject design with a 62-year-old man who exhibited aprosodia secondary to a right-hemisphere stroke. Three treatment phases were utilized: a prosody repetition strategy, a cognitive linguistic self-cueing strategy, and a facial expression cross-cueing strategy. Two weeks of treatment were alternated with 2 weeks of no treatment. Preliminary findings suggested the most powerful treatment effect resulted from the prosody repetition treatment. Stringer (1996) also treated a single case of aprosodia. His patient was a 36-year-old female whose aprosodia resulted from traumatic brain injury. He combined two treatments that he called pitch biofeedback and expression modeling. The pitch biofeedback component of the treatment provided acoustic feedback via the Visipitch. Expression modeling required the patient to imitate the clinician's tone of voice and facial expression. Treatment duration was two months. Prosody imitation, prosody production, gesture imitation, and gesture production all improved. Results from these two studies support cautious optimism about the influence of behavioral treatments on aprosodia. However, if behavioral...