The effects of audibility and novel word learning ability on vocabulary level in children with cochlear implants

Abstract

Objectives

A novel word learning (NWL) paradigm was used to explore underlying phonological and cognitive mechanisms responsible for delayed vocabulary level in children with cochlear implants (CIs).

Methods

One hundred and one children using CIs, 6–12 years old, were tested along with 47 children with normal hearing (NH). Tests of NWL, receptive vocabulary, and speech perception at 2 loudness levels were administered to children with CIs. Those with NH completed the NWL task and a receptive vocabulary test. CI participants with good audibility (GA) versus poor audibility (PA) were compared on all measures. Analysis of variance was used to compare performance across the children with NH and the two groups of children with CIs. Multiple regression analysis was employed to identify independent predictors of vocabulary outcomes.

Results

Children with CIs in the GA group scored higher in receptive vocabulary and NWL than children in the PA group, although they did not reach NH levels. CI-aided pure tone threshold and performance on the NWL task predicted independent variance in vocabulary after accounting for other known predictors.

Discussion

Acquiring spoken vocabulary is facilitated by GA with a CI and phonological learning and memory skills. Children with CIs did not learn novel words at the same rate or achieve the same receptive vocabulary levels as their NH peers. Maximizing audibility for the perception of speech and direct instruction of new vocabulary may be necessary for children with CIs to reach levels seen in peers with NH.

Keywords:

• Deafness
• Cochlear implant
• Pediatric
• Novel word learning
• Incidental learning
• Audibility
• Normal hearing vocabulary

Acknowledgements

Special thanks to Christine Brenner for help with data analysis and to Michelle Gremp and Brent Spehar for help with development and pilot testing of earlier versions of the Novel Word Learning task. Thanks also to the children and families who volunteered to participate as well as the schools and audiologists whose contributions made this research possible.

Grants received by authors

This work was funded by grants R01DC004168 (Nicholas) and K23DC008294 (Davidson) from the National Institute on Deafness and Other Communication Disorders.