Prosody and Emotion: Acoustic Analysis of “Emotional Tone” in Nondominant Hemisphere Damaged Subjects

Abstract

Hemispheric specialisation of prosody has been widely discussed (Colsher & Cooper, 1987; Ross et al., 1988; Ryalls & Behrens, 1988; Ryalls, 1988; Shapiro & Danly, 1985; Tompkins & Flowers, 1985). The right cerebral hemisphere has been implicated in the control of processes for the reception and expression of emotional prosody (Behrens, 1988; Ryalls & Behrens, 1988; Shapiro & Danly, 1985; Kreiman & Van Lancker, 1988). The results of these studies are not conclusive however, and specialisation of emotional prosody to the right cerebral hemisphere remains an issue for discussion (Ryalls & Behrens, 1988). Prior to the development of acoustic analysis techniques, evaluation of prosody relied on perceptual judgments (Ryalls & Behrens, 1988). This technique lacks reliability for naive judges and even trained linguists are unable to produce consistent perceptual judgements about prosody (Ryalls, 1988). According to Ryalls (1988), the only way to verify subjective judgements is through the objectivity of acoustic analysis. The purpose of this study therefore was to investigate the effect of right hemisphere damage on the perception and production of emotional prosody. Eight male patients with altered prosody following strokes in the region of the middle cerebral artery of the right cerebral hemisphere and 4 male normal subjects with no history of neurological damage, participated in the study. Each subject was required to read ten semantic-ally neutral sentences using first a “neutral”, then, “happy”, “angry” and “sad” tone of voice into the tape recorder. Acoustic analysis including measures of fundamental frequency, intensity and duration as well as the associated variances was performed on all productions. A receptive version of this task was also completed by each subject. No significant differences were found between the two groups on the receptive scores, but this may have been due to the nature of the task. In the production task Right CVA subjects produced significantly shorter utterances than the controls in all conditions. There was also a significant interaction between standard deviation of fundamental frequency and group. Results are discussed in light of current theories of emotion and advances in acoustic analysis.