Investigation of phoneme discrimination and localization skills in pediatric cochlear implant and contralateral auditory brainstem implant users

The aim of this study is to determine the impact of different modalities on performance in children with cochlear implants (CI) and contralateral auditory brainstem implants (ABI) by evaluating phoneme discrimination, localization, and hearing-related quality of life. The study included 17 participants, ages 6 to 18, who used CI and contralateral ABI. All participants underwent a phoneme discrimination test, an azimuth localization test, and a hearing-related quality of life assessment. Phoneme discrimination and azimuth localization tests were performed in three different conditions: CI, ABI, and bilateral. Significant differences were found in the triple comparisons in the phoneme discrimination test (p=0.004). In pairwise comparisons, the bilateral phoneme discrimination score was significantly higher compared to the only ABI listening condition (p=0.003), and no significant difference was observed between the CI and the bilateral condition (p>0.05). In the azimuth localization test, no significant difference was found in triple comparisons (p>0.05). In the bilateral condition, hearing-related quality of life scale ratings were positively and strongly correlated with phoneme discrimination scores (r=0.873, p=0.001). In the listening condition with ABI, a moderately positive correlation was found between phoneme discrimination score and azimuth localization (r=0.525, p=0.030). It was found that with ABI, localization skill was predictive of bilateral localization skill, and bilateral phoneme discrimination was predictive of hearing-related quality of life. To the best of our knowledge, this is the first study, other than case reports, in which holistic auditory evaluation was performed in children using CI and contralateral ABI, and the contributions of CI and ABI on performance were investigated.