Quantification of the stapedial reflex reveals delayed responses in autism.

Spates et al. (2013) tested the acoustic stapedial reflex (ASR) in the toddlers with autism and 24 matched controls. They used a tiny ear probe that puffs air and plays clicks while a computer records the reflex.

The team looked at three things: how loud the click had to be to trigger the reflex, how fast the reflex started, and whether both ears reacted the same way.

Autistic toddlers needed a softer click to trigger the reflex, but the reflex started about 0.3 milliseconds later. One ear often reacted before the other, while control kids showed even timing.

These tiny delays and asymmetries showed up before most behavioral red flags, hinting that the brain-stem pathway that moves the tiny stapes bone is off-track in autism.

Santos et al. (2017) found the same age group had bigger ABR wave I, another brain-stem sound response. Together the papers say the lower parts of the auditory pathway fire differently in autism, even when kids pass standard hearing tests.

Russo et al. (2009) moved up to the cortex and showed autistic kids process speech in quiet only as well as typical kids do in noise. The pattern is consistent: sluggish timing starts low in the brain-stem and climbs to higher speech areas.

Ip et al. (2024) warn that one in nine preschoolers with autism who passed newborn hearing screens later showed hearing loss. Richard’s quick ASR check could catch both early autism risk and late-onset loss in the same five-minute test.

You already watch for eye contact and language delays. Adding a 5-minute ASR screen at intake gives you a cheap, objective red flag before behavioral signs solidify. If the reflex is slow or lopsided, refer for full audiology and flag the case for early intensive teaching. The test fits inside a standard hearing booth visit, so you lose no table time.