Cochlear implants (CIs) are the state-of-the-art therapy for individuals with severe to profound hearing loss, providing them with good functional hearing. Nevertheless, speech understanding in background noise remains a significant challenge. The purposes of this study were to: (1) conduct a novel within-study comparison of speech-in-noise performance across ages in different populations of CI and normal hearing (NH) listeners using an adaptive sentence-in-noise test, and (2) examine the relative contribution of sensory information and cognitive-linguistic factors to performance. Forty CI users (mean age 20 years) were divided into "early-implanted" <4 years (n = 16) and "late-implanted" >6 years (n = 11), all prelingually deafened, and "progressively deafened" (n = 13). The control group comprised 136 NH subjects (80 children, 56 adults). Testing included the Hebrew Matrix test, word recognition in quiet, and linguistic and cognitive tests. Results show poorer performance in noise for CI users across populations and ages compared to NH peers, and age at implantation and word recognition in quiet were found to be contributing factors. For those recognizing 50% or more of the words in quiet (n = 27), non-verbal intelligence and receptive vocabulary explained 63% of the variance in noise. This information helps delineate the relative contribution of top-down and bottom-up skills for speech recognition in noise and can help set expectations in CI counseling.
Keywords: Cochlear implant; bottom-up processing; congenital hearing loss; hearing impairment; postlingually deafened; prelingually deafened; progressive hearing loss; speech recognition; speech-in-noise; top-down processing.