Vocabulary development in Mandarin-speaking children with cochlear implants and its relationship with speech perception abilities.

Yuan and team tracked 47 Mandarin-speaking toddlers who got cochlear implants. All kids were younger than three when the device was switched on. The researchers tested vocabulary size every three months for one year. They also asked moms how far they went in school.

No control group, just before-and-after scores on a picture-naming test.

Kids implanted before age two rocketed from 20 words to 240 words in 12 months. That pace matched hearing peers. Children implanted after age two grew slower. Moms with college degrees had kids who caught up fastest.

Bottom line: early surgery plus educated moms equals near-normal vocabulary.

Libero et al. (2016) looked at the same group—toddlers with cochlear implants—but saw gloomier numbers. Most of their kids stayed behind on both words and grammar. The gap: E et al. counted kids implanted up to age five and did not split by maternal education. When you zoom in on the under-three, well-educated-mom slice, the delay shrinks.

Chiviacowsky et al. (2013) also found that early language input—Cued Speech before kindergarten—let deaf kids read on level by second grade. Both papers agree: start language support early, whether through implants or visual cues.

Meng et al. (2026) showed Mandarin-speaking autistic toddlers learn grammar in the same order as typical kids, just slower. Yuan’s CI toddlers mirror that pattern for vocabulary: same steps, faster speed if implanted early.

If you serve Mandarin-speaking families, push for implant surgery before the third birthday. Coach highly educated parents to keep talking and reading; coach less-educated parents extra hard because their kids need more reps. Use quick vocabulary checks every few months to be sure growth stays steep. When growth stalls, add auditory-memory drills—E et al. showed that skill keeps words coming.