목적: To investigate to know the benefits of different bilateral hearing modes using CI. 방법:40 bimodal users were divided into three groups as follows Gr. 1 - Bimodal users, Gr. 2 bilateral CIs (Bi-CI) users who had poor bimodal performance, Gr. 3 - Bi-CI users with some bimodal benefits. To determine bimodal benefits, performance of Gr. 1 was compared to the scores of Bi-CI users, audiologically matched to Gr. 1 members, in areas of speech in quiet and noise, music perception, and sound localization. Performances of Gr. 2 and Gr. 3 were also compared to the pre and postoperative (2nd CI) performance using measures such as speech in quiet and noise, music perception, and sound localization test. 결과:The speech perception in quiet and noise seemed to be better in the group of bilateral CI users, while music perception and localization ability were likely to be better in the group of bimodal users. All Bi-CI users who had no benefits with bimodal mode showed significant improvements in speech in noise, music, and localization. Although most Bi-CI users who had some benefits with bimodal mode showed significant improvement in speech in noise, music, and localization, some users preferred to use HA (Hearing Aid) for listening to music rather than CI. In particular, all Bi-CI users using acoustic sound (EAS users) presented better binaural benefit more than bimodal users. 결론:Although the advantage of bilateral hearing modes in both of bimodal and Bi-CI worked regardless of the sound source and conditions, Bi-CI mode has shown limited benefits in some situations, compared to bimodal mode. It seemed that the combination of acoustic sound in Bi-CI mode might give us the best solution to those limitations from Bi-CI mode.