Baby’s Noises Signal Readiness for Speech

The grunts and squeaks that babies make before they start babbling may not be random sounds, but rather fundamental building blocks of language development. From the first month of life, babies make these sounds in batches rather than sporadically, indicating that they are “practicing” before learning to talk.

“Our findings suggest that infants are practicing a range of vocalizations from the first few months of life, laying the foundation for further language development,” said Dr. Yoo Hyun-ju at the University of Alabama, Tuscaloosa.

Previous studies have looked at babies’ babbling around the age of 5 to 7 months, Yu said, but little research has been done on the three most common types of more basic infant vocalizations: squeaks, grunts and mid-pitched sounds called boccants.

To learn more, Yu and his colleagues asked the parents of 130 infants – 71 boys and 59 girls who appeared to be developing normally – who lived in or near Atlanta, Georgia, to place a small voice recorder in the infants’ clothing pockets once a month, for 16 hours a day, for the first two years of their babies’ lives.

The researchers randomly selected 21 five-minute segments from each baby’s recordings each day, and categorised each sound the baby made into something like a squeak, grunt, cry or blowing a raspberry.

The team found that all of the babies produced bursts of squeals, grunts, or both, which meant that the sounds occurred more frequently over the five-minute period than merely by chance, and were therefore probably preparations for speech rather than just random noises, Yoo said.

Overall, 40 percent of the screeches and growls occurred together. In 61 percent of the recordings, the chunks were either screeches or growls, but not both.

For 87 percent of babies, the preference for either the squeak or grunt clustering was linked to age, with squeaks being especially prevalent in babies over five months of age. This could be because higher-pitched squeaks require greater control of the vocal cords, but the finding needs further investigation, Yoo says.

The researchers also found that the babies had crowding of speech organs, but they did not focus on these in their analysis.

Surprisingly, even the youngest babies were able to produce clusters of sounds, Yoo said. Infants begin to “play” with language around 3 to 4 months of age.However, she says, further studies are needed to confirm these findings: “We do not believe that this pattern of age results provides a definitive conclusion regarding the clustering of phonetic categories.”