Babies 'squeal and growl in distinct patterns throughout first year of life'

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Babies squeal and growl in distinct "clustering" patterns throughout the first year of life, reveals new research.

The apparently random early vocal attempts are actually key to the development of speech, say scientists.

The first ever large-scale observation of babies' vocalisations using all-day home recordings suggests they actively engaged in noisemaking play and sound practice.

The American and Austrian research team identified the most common baby phonation categories as "vocants" - or vowel-like sounds - "squeals" and "growls".

They investigated whether babies group specific noises in a non-random way, which would suggest practice or play.

The team analysed recordings from 130 English-learning, normally-developing babies recorded all day in their own homes in their first year of life.

A total of 21 five-minute samples were randomly chosen from each baby recording.

The researchers categorised each vocalisation made in every sample into vocants, squeals, and growls - as well as "other" sounds.

Study co-author Dr HyunJoo Yoo said: "Forty per cent of all analysed squeals and growls appeared in significant clusters across all infants."

"Over 60 per cent of the five-minute sessions showed a significant amount of clustering focusing on either squeals or growls, not both in one session."

The findings, published in the journal PLoS One, also revealed that 87 per cent of the babies showed at least one age where their recordings had "significant squeal clustering" and at least one age where their recordings had "significant growl clustering" - with none of the babies demonstrating no clustering.

The research team acknowledged that their sound categorising approach, while enabling them to collect a large amount of data, likely "oversimplified" complexities and nuances in baby vocalisations.

But thy say the data gathered was "sufficient" to see clear patterns in individual babies as well as across the entire group, suggesting a possible pathway for language development warranting further investigation.

Dr Yoo, an Assistant Professor at the University of Alabama, said: "Active vocal exploration and vocal category formation are fundamental to subsequent language development."

She added: "The present study represents the first empirical investigation of early vocal category formation."

"Infants not only spontaneously produce speech-like vocalisations, but also actively explore and practice different types of vocalisations from the first months of life."