Acoustic analyses support subjective judgments of vocal emotion

Subjective human judgments of emotion in speech have been considered to be less reliable than acoustic analyses in scientific studies, but acoustic analyses have had limited ability to detect subtle vocal nuances that give useful social information about human intent and meaning to discourse partners. Two post hoc analyses were undertaken to determine if results from acoustic analyses of vocalizations were related to subjective judgments of vocal affect (affective prosody). Acoustic analyses of fundamental frequency (F(o)) and subjective judgments of emotional content of vocal productions from two studies underwent statistical analyses: Study 1-vocal repetition of sentences using 6 basic emotions in 24 detoxified alcoholics and 15 controls; study 2-quality/quantity of "motherese" speech directed to 52 infants in Cambridge, England. Ratings of emotion indicators for both studies were done by female researchers of different ages and cultural/language backgrounds. In both studies, acoustic analyses of F(o) elements in utterances accounted for approximately 50% of the effect when modeling subjective emotion accuracy and emotion intensity ratings, using linear regression analyses. Acoustic analyses of F(o) are positively associated with subjective judgments of emotion indicators, and speakers who cannot vary F(o) are unable to convey emotion accurately to communication partners. Yet acoustic analyses are limited in comparison to the exquisite complexity of the human auditory and cognitive systems. Subjective judgments of emotional meaning in speech can be a reliable variable in scientific inquiry and can be used for more complex, subtle studies of speech communication and intentionality than acoustic analyses.