SLPCohortJournal of autism and developmental disorders2025

Foundations of Vocal Category Development in Autistic Infants.

Pumpki Lei Su, Hyunjoo Yoo, Gordon Ramsay and 8 others

PMID 38403868

WHAT IT FOUND

Autistic infants clustered their vocal play (squeals and growls) at the same rate as typically developing infants.

The amount of clustering did not predict language skills or autism severity at age two, so this early vocal pattern is not a useful marker for diagnosis.

Key findings

01The percentage of recordings showing significant clustering of squeals or growls did not differ significantly between typically developing and autistic infants.

02The extent of vocal clustering in autistic infants did not correlate significantly with language outcomes or autism severity scores at two years of age.

03Both groups showed high rates of clustering, with more than 60% of recordings from each group displaying significant patterns of vocal play.

STILL TO COME

How it was doneWhat they foundWhat it means for SLPs

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What it does not show

The study focused only on three specific vocal categories (vocants, squeals, growls), ignoring other vocal features like prosody or pitch variability which may differ in autism. Real-time coding by humans may have missed subtle variations in vocal quality, as coders had to choose the single most salient category for each utterance. The sample of autistic infants consisted largely of those with an older sibling with autism, which may limit generalizability to autistic infants without a family history. Only a small fraction of the total recording time (about 1/6) was analyzed, which likely underestimates the total amount of clustering.

Declared interests

One author (DKO) is an unpaid member of the LENA Scientific Advisory Board. LENA technology was used for data collection. No other competing interests were declared.

The easy way to misread this

Do not conclude that autistic infants have atypical vocal play patterns. The study found that clustering rates were statistically similar between groups, and the lack of correlation with outcomes means this specific vocal behavior is not a predictive marker for autism or language delay.

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