Brainstem and middle latency auditory evoked potentials in autism and developmental language disorder.

The team wired up kids with autism and kids with language delays to an EEG cap. They played clicks and tones while recording two early brain waves: brainstem and mid-latency responses.

These waves happen before the child even thinks about the sound. They tell us if the ear and low-level brain circuits send the signal up the line.

Both groups had normal brainstem and mid-latency waves. The timing and size of the waves looked just like typical kids.

If the early relay stations work fine, later processing stages must explain why many autistic learners struggle with sound.

Hogg et al. (1995) used the same lab and same kids but looked at later cortical waves. They did find weaker responses when sound intensity changed. Together the two papers draw a line: low-level wiring is intact, but intensity coding higher up is not.

Iwata (1993) later pooled many ABR studies and saw mixed results. The review says hearing loss, not autism, often causes odd latencies. Barthelemy et al. (1989) already controlled for hearing, so their clean null result fits the review’s warning.

Wagner et al. (2025) push the story younger. Nine-month-old high-likelihood infants already show weak speech lateralization. Normal brainstem waves in preschoolers can coexist with atypical cortex in babies, showing timing matters.

When a learner with autism ignores speech, do not blame faulty ears. Check hearing once, then shift focus to teaching the brain how to weigh sounds. Use clear intensity changes, visual cues, and repetition to train later auditory cortex, because the early wires are already working.