How Parents Talk to Infants and Dogs

A recent Hungarian study published in Nature Scientific Reports reported that the acoustic features of parents’ infant-directed speech (IDS) and dog-directed speech (DDS) are affected by parental gender and social context, suggesting that “people adapt their prosodic features to the acoustic preferences and emotional needs of their audience,” the study’s investigators wrote.

DDS and IDS are acoustically and linguistically similar, differing from adult-directed speech (ADS) in that they are more repetitive and have a higher overall pitch. Parents use this higher pitch, particularly for IDS, in natural social situations like storytelling.

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Women alter their DDS according to social context—higher pitch when greeting a dog and lower pitch when leaving a dog. Overall, though, little is known about how gender and communication context affect the acoustic features of IDS and DDS, highlighting an important research gap. Previous studies comparing IDS and DDS were limited by using only a single context, like playing with infant or dog.

Speech Evaluation

Researchers recruited 21 families with 39 parents (21 mothers, 18 fathers) who had a biological child younger than 30 months old and an adult pet dog. The parents were divided into 3 groups according to their child’s age:

• Early pre-linguistic: 5 months old

• Late pre-linguistic: 16.5 months old
• Emerging language: 25.5 months old

Parents were video-recorded providing speech samples in multiple contexts: 3 “free” contexts (storytelling, task solving, teaching) that mirrored natural social interactions and 1 “fixed” context (predefined sentences).

For each context, parents spoke to their infant, dog, or adult experimenter and the mean fundamental frequency (pitch), pitch range, and hyperarticulation were determined. In human speech, the researchers explained, mean pitch relates to communicating affection, pitch range is used for gaining an addressee’s attention, and hyperarticulation is associated with language tutoring.

Free Speech

Overall, mean pitch was higher for IDS and DDS than for ADS and was highest with DDS. Several specific differences in mean pitch were observed:

• Mean pitch was higher for mothers than fathers.
• Among speech contexts, pitch was typically highest for “task solving.”
• Child’s age significantly affected IDS, but not DDS or ADS. IDS pitch was highest in parents of the youngest infants.
• Only fathers adjusted mean pitch according to child’s age, with pitch being highest when speaking to the youngest infants.

Generally, pitch range was similar for IDS and DDS and broader than that for ADS. As with mean pitch, only fathers adjusted pitch range according to child’s age, with the range being broadest when speaking to the youngest infants. In addition, pitch range varied among speech contexts; for example, mothers used a broader pitch range for “task solving” than for “storytelling” or “teaching.”

Fixed Speech

Compared with the fathers, the mothers had a higher mean pitch and broader pitch range when saying predefined sentences. Across speech types (IDS, DDS, ADS), child’s age did not significantly affect mean pitch and had few significant effects on pitch range.

Vowel hyperarticulation was used more often with IDS than with DDS or ADS and more frequently by mothers than fathers.

Bringing It Together

The researchers concluded that adults have similar speech registers for infants and dogs, characterized by high pitches and broad pitch ranges. Yet, they noted, the acoustic features of IDS and DDS depend on gender and situation and can be adjusted according to the addressee’s language competence and emotional and attentional needs.

For the future, “more research is needed to better understand the relationship between contextual changes and varying characteristics of infant- and dog-directed talk,” they said.

Dr. JoAnna Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.