Vocal Emotion in Pet-Directed and Infant-Directed Speech: Similar Sounds and Functions, but Different Determinants

Pet-directed speech and infant-directed speech sound similar. This study concerned this similarity, specifically with respect to (a) the relative degree of emotion in speech to pets and infants, (b) if the degree of emotion is affected by whether the speaker has only a pet, only an infant, or both a pet and an infant, and (c) any differences in the social or psychological determinants of emotion in speech to pets versus infants. Emotion in speech is conveyed by various factors, most notably via the semantics and prosody of the speech. Here we compared the prosody of pet-owners' and parents' speech; that is, their "vocal emotion" in three groups of women: those only with a pet (n = 10, only pet-directed speech recorded), only an infant (n = 10, only infant-directed speech recorded), or both a pet and infant (n = 10, both pet- and infant-directed speech recorded). The degree of vocal emotion, derived from naive listeners' ratings on a well-established set of communicative intent scales, was found to be similar in the pet-directed speech of women who had only a dog and the infant-directed speech of those who had only an infant. However, for women with both a pet and an infant, vocal emotion was significantly lower in their pet- than their infant-directed speech. Regression analyses showed no social/psychological predictors of vocal emotion in infant-directed speech, but there were both positive and negative predictors of pet-directed speech. The better the pet owner's social support, the greater vocal emotion in their pet-directed speech, and if the pet owner also had an infant, then there was less vocal emotion. Results are discussed in terms of the similarities and differences between vocal emotion in pet- and infant-directed speech and the possible determinants of the differences.