Effect of bimodal amplification according to the residual hearing level.

Objectives: Bimodal amplification shows better cognition of sounds through the improvement of head shadow effect, binaural squelch effect and binaural summation effect. In patients received unilateral cochlear implantation, the impact of hearing aids in the contralateral ear may depend on the residual hearing level, duration of hearing aid use, and others. In this study, we collected patients with bimodal amplification and aimed to evaluate the factors related to the hearing performance. Materials and Methods: This retrospective study included forty-nine patients who used cochlear implantation in one ear and a hearing aid in the contralateral ear for more than one year. Hearing level, an inner ear anomaly, and benefit of amplification were collected. A subjective benefit of amplification was measured by the Korean version of the Speech, Spatial and Qualities of Hearing Scale (KSSQ). K-SSQ score was calculated by the summation of each point of 12 questions (-5 ~ +5), and +24 points were used to be a cut off value of positive gain. Results: The average age of cochlear implantation is 6.7 years old. Thirty-six out of 49 (73.5%) showed a positive gain in K-SSQ when the hearing aids were used in the presence of cochlear implantation. Monosyllabic word recognition was better in the bimodal stimulation (8.4% increase). K-SSQ score showed a significant correlation with the low-frequency hearing level with contralateral cochlear implantation only and with the hearing level at 250 and 500Hz with bimodal amplification. There was also a significant correlation between the speech discrimination score and the K-SSQ score after the bimodal amplification. K-SSQ score showed no significant correlation with age at implantation, duration of use of cochlear implantation, and duration of use of hearing aid. Conclusions: A subjective benefit of amplification has a correlation with the low-frequency residual hearing level in the ear with hearing aid. [ABSTRACT FROM AUTHOR]