Nonword Repetition Assessing Auditory and Cognitive Abilities in Adult Cochlear Implant Users

Phonological processing is essential for understanding spoken language and depends on auditory, cognitive, and linguistic skills. Although cochlear implants (CIs) can restore audibility in adults with sensorineural hearing loss, the speech recognition outcomes vary considerably. One factor previously found to underlie this variability is phonological processing skills, which may be additionally impaired by advancing age. This study examined phonological processing using a nonword repetition task (NWRT) with experienced adult CI users and normal-hearing (NH) peers. We also examined age-related changes in phonological processing and explored individual differences in auditory, cognitive, and linguistic factors that might predict NWRT variability among CI users.

Sixty-eight CI users and 44 NH adults older than 50 years completed an audiovisual NWRT and a battery of auditory, cognitive, and linguistic assessments, including measures of spectrotemporal resolution, reading efficiency, working memory, vocabulary, and nonverbal reasoning.

CI users demonstrated reduced accuracy on NWRT compared with NH peers. CI users also exhibited stronger age-related impairments in NWRT performance, suggesting compounding effects of hearing loss, degraded CI signals, and advanced age. Spectrotemporal resolution was the strongest contributor to NWRT performance among CI users, followed by reading efficiency, vocabulary size, and nonverbal reasoning.

Our findings demonstrate that adult CI users experience challenges in phonological processing, with advancing age contributing to this decline. Performance on the NWRT reflects the combined influence of auditory (spectrotemporal resolution), cognitive (nonverbal reasoning), and linguistic (reading efficiency and vocabulary knowledge) factors and with spectrotemporal resolution emerging as the primary contributor.