A psychologist has discovered a connection between a baby’s initial sounds and heart rate.
The gentle coos and soft sounds of a baby’s first expressions, like sweet whispers that delight loving parents, actually signal that the baby’s heart is rhythmically working in sync with their nascent speech abilities.
Jeremy I. Borjon, an assistant professor of psychology at the University of Houston, has shared findings in the Proceedings of the National Academy of Sciences that the early sweet sounds and attempts at speech in babies are closely related to their heart rate. These results could enhance our understanding of how language develops and provide early signs of potential speech and communication challenges.
For babies, creating recognizable speech involves more than just thinking; it’s a motor skill that demands the coordination of various muscles throughout their body. This coordination is directly tied to the changes in their heart rate.
Borjon explored whether heart rate variations occur alongside vocalizations and word formation in babies aged 24 months. He found that these heart rate changes correspond to when vocal sounds are made, as well as how long they last and the likelihood of being perceived as actual words.
“Heart rate tends to fluctuate naturally in all mammals, with a steady rhythm of increasing and then decreasing. Interestingly, infants were most inclined to vocalize when their heart rate hit a peak (maximum) or a trough (minimum),” Borjon explained. “Vocalizations produced at the peak were longer than would be expected by chance, and those made just before the trough, while the heart rate is slowing down, were more often recognized as words by those unfamiliar with the babies’ sounds.”
Borjon and his team recorded 2,708 vocalizations from 34 infants aged 18 to 27 months as they interacted with caregivers. Typically, infants at this stage do not articulate full words, and only a small portion of their sounds were reliably identified as words by untrained listeners (10.3%). For the study, the team examined the heart rate patterns accompanying all types of sounds, whether it be laughter, babbling, or cooing. “Every sound an infant produces plays a role in their brain and body learning to work together, ultimately leading to the development of speech,” stated Borjon.
As infants mature, their autonomic nervous system — responsible for controlling body functions like heart rate and breathing — also develops. The early years are characterized by vital transformations in cardiovascular and respiratory functions, which continue to evolve throughout a person’s life.
“The link between recognizable vocal sounds and a slowing heart rate may suggest that the successful development of speech is partly influenced by infants experiencing consistent patterns of autonomic activity as they grow,” Borjon noted.
“Exploring how the autonomic nervous system connects with infant vocalizations during development is an important area for future research, which could improve our understanding of how language develops and reveal risk factors for atypical language growth,” Borjon concluded.
