Investigating Receptive Vocabulary in Children With Cochlear Implants : The Hearing Journal

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Cochlear Corner

Investigating Receptive Vocabulary in Children With Cochlear Implants

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doi: 10.1097/01.HJ.0000899332.48320.e7
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Cochlear implants are invaluable hearing devices for many profoundly deaf children, but the language skills of children with cochlear implants do often still lag behind that of their peers with typical hearing. Receptive vocabulary is one such language area where a skill gap exists. The gap potentially indicates that current rehabilitation programs might not offer sufficient language development support. To investigate further, the authors of “Receptive Vocabulary of Children With Bilateral Cochlear Implants From 3 to 16 Years of Age,” which was published in Ear and Hearing, completed a cross-sectional study assessing the vocabulary performance of children with cochlear implants between ages 3 and 16 years.

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WIDE VARIATION IN PERFORMANCE

Language outcomes typically vary a great deal in children with bilateral early implantation, even among relatively homogenous population samples. This population’s language performance typically varies much more than the range seen among typical hearing peers, but previous studies have not paid much attention to whether or not that difference in range is statistically significant. Higher-than-normal variation could indicate that a study group’s average vocabulary performance is less representative of the experiences of individuals. However, wide variation might be caused by the impact of outliers in the data, so a much closer inspection of this phenomenon is warranted.

HYPOTHESIS

Uncertainty exists in the previous available research on receptive vocabulary skills of children with cochlear implants and children with typical hearing. Some evidence indicates a nonlinear relationship between age and vocabulary growth.

“Similar to previous studies, we expected to find a deficit in CI users’ vocabulary scores and a potentially non-linear effect of age on the size of the vocabulary gap,” wrote the study authors. “We also expected that child-level characteristics such as age at implantation and communication mode would explain some of the inter-individual variability in vocabulary skills. Regarding the effect of age on vocabulary, we were interested in whether the difference between CI users and children with TH would be larger around the time that the children enter school, and what would happen in the years after that.”

STUDY DESIGN AND RESULTS

The researchers conducted a retrospective cross-sectional study with matched controls at the Norwegian national cochlear implant center at Oslo University Hospital. The study included 88 children (mean age 8.7 years; range 3.2 to 15.9 years; 43 girls, 45 boys) who received bilateral cochlear implants before age 3 years and compared them with two groups of peers with typical hearing. One of the typical hearing groups was matched for maternal education, gender, and chronological age. The second group was match for maternal education, gender, and hearing age. Researchers used the British Picture Vocabulary Scale.

The study found that cochlear implant users did indeed have poorer receptive vocabulary compared with their peers with typical hearing. However, a significant nonlinear U-shaped effect of age on the vocabulary performance scores was observed in cochlear implant users. The difference of the matched typical hearing children was the largest (23.9 standard points, on average) around 8.7 years of age and smaller toward the beginning and end of the age range. Other notable results included a pattern that the following factors all seemed to be predictive of cochlear implant users’ receptive vocabulary skills: chronological age, hearing age, simultaneous versus sequential implantation, communication mode at school, and social integration.

FINAL THOUGHTS

As expected, the receptive vocabulary of children with cochlear implants was smaller than observed in their peers with typical hearing, but the degree of deficit was correlated with age and was the greatest in children attending early primary school.

“The results emphasize that continuous monitoring and support are crucial to avoid far-reaching negative effects on the children’s development and well-being,” wrote the study authors.

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