Comparison of speech perception between monaural and binaural hearing in cochlear implant patients

OBJECTIVE: To assess the advantages of binaural hearing for cochlear implant (CI) users using a hearing aid (HA) for the contralateral ear. MATERIAL AND METHODS: The subjects comprised 3 males and 3 females (age range 48-84 years). All of them had been using a CI and HA for > 6 months. Their speech perception was examined in quiet using monosyllables and Japanese Hearing in Noise Test (J-HINT) sentences. Speech perception in noise was examined using J-HINT sentences. Late cortical waves were measured while subjects listened to 1 kHz frequent and 2 kHz target tone stimuli. The latency of the event-related potential (P300) wave was compared for monaural and binaural hearing conditions. RESULTS: Three subjects showed significantly better results for binaural than monaural (CI alone) hearing for monosyllables and HINT sentences (p < 0.05; paired t-test). Subjects with better speech perception had been using an HA for longer than those with poor performance (18.3 vs 4.0 years). The overall average score was better for binaural than monaural hearing in the speech perception test under quiet and noisy conditions. Comparison of the latency of the P300 wave under monaural and binaural hearing conditions showed a significantly shorter latency for the latter (p = 0.02; paired t-test). CONCLUSIONS: Although the use of an HA alone showed marginal benefit for CI users, binaural hearing (CI+HA) resulted in a significant improvement in speech perception under various circumstances.