Acquisition of voice onset time in toddlers at high and low risk for autism spectrum disorder.
Toddlers who later develop autism may already muddle the /b/-/p/ timing, even with normal language scores.
01Research in Context
What this study did
Chenausky et al. (2017) followed toddlers who were later diagnosed with autism. They recorded how the kids said the sounds /b/ and /p/ at 18, 24, and 36 months. These sounds differ only in voice onset time—how soon the vocal cords vibrate after the lips open.
The team compared the toddlers who later got an ASD label with peers who did not. All kids had normal language scores on standard tests. No teaching or therapy was given; the study just watched natural speech develop.
What they found
By 36 months, the ASD group often blurred the /b/-/p/ difference. Their voice onset times overlapped more, so the sounds were less clear. Surprisingly, this happened even though every child scored within the average range on language tests.
The finding was negative: typical tests missed a subtle speech-timing gap that showed up in acoustic measurements.
How this fits with other research
Irwin et al. (2022) extends this work to older children. They showed school-age kids with ASD rely less on a speaker’s mouth when hearing /ba/ versus /a/. Together the two studies trace a line: early acoustic timing slips (Karen) and later weaker audiovisual use (Julia) both shape speech perception.
Duerden et al. (2012) offers hope. French children with specific language impairment improved voicing discrimination after only nine short computer games. The training sharpened the same acoustic contrast—/b/ versus /p/—that Karen found slipping in toddlers headed for ASD.
Mantzoros et al. (2022) supply the intervention map. Their meta-analysis shows that response interruption, self-management, and interactive play cut automatically reinforced vocal stereotypy. If abnormal voicing feeds such stereotypy, those top tactics could be adapted early.
Why it matters
You can spot risk sooner. Add a quick acoustic check—measure voice onset time with free phone apps—when a toddler’s language scores look fine but social red flags exist. Early blur may open a window for short, game-like voicing drills before clearer stereotypy sets in.
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Join Free →Record the child saying ‘big pig’ twice; inspect the wave-form for /b/ and /p/ overlap—if the bursts look alike, flag for speech-language follow-up.
02At a glance
03Original abstract
Although language delay is common in autism spectrum disorder (ASD), research is equivocal on whether speech development is affected. We used acoustic methods to investigate the existence of sub-perceptual differences in the speech of toddlers who developed ASD. Development of the distinction between b and p was prospectively tracked in 22 toddlers at low risk for ASD (LRC), 22 at high risk for ASD without ASD (HRA-), and 11 at high risk for ASD who were diagnosed with ASD at 36 months (HRA+). Voice onset time (VOT), the main acoustic difference between b and p, was measured from spontaneously produced words at 18, 24, and 36 months. Number of words, number of tokens (instances) of syllable-initial b and p produced, error rates, language scores, and motor ability were also assessed. All groups' mean language scores were within the average range or slightly higher. No between-group differences were found in number of words, b's, p's, or errors produced; or in mean or standard deviation of VOT. Binary logistic regression showed that only diagnostic status, not language score, motor ability, number of words, number of b's and p's, or number of errors significantly predicted whether a toddler produced acoustically distinct b and p populations at 36 months. HRA+ toddlers were significantly less likely to produce acoustically distinct b's and p's at 36 months, which may indicate that the HRA+ group may be using different strategies to produce this distinction. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1269-1279. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.
Autism research : official journal of the International Society for Autism Research, 2017 · doi:10.1002/aur.1775