Auditory Training in Patients With Unilateral Cochlear Implant and Contralateral Acoustic Stimulation

In Brief Objectives: It was hypothesized that auditory training would allow bimodal patients to combine in a better manner the low-frequency acoustic information provided by a hearing aid with the electric information provided by a cochlear implant, thus maximizing the benefit of combining acoustic (A) and electric (E) stimulation (EAS). Design: Performance in quiet or in the presence of a multitalker babble at +5 dB signal to noise ratio was evaluated in seven bimodal patients before and after auditory training. The performance measures comprised identification of vowels and consonants, consonant-nucleus-consonant words, sentences, voice gender, and emotion. Baseline performance was evaluated in the A-alone, E-alone, and combined EAS conditions once per week for 3 weeks. A phonetic-contrast training protocol was used to facilitate speech perceptual learning. Patients trained at home 1 hour a day, 5 days a week, for 4 weeks with both their cochlear implant and hearing aid devices on. Performance was remeasured after the 4 weeks of training and 1 month after training stopped. Results: After training, there was significant improvement in vowel, consonant, and consonant-nucleus-consonant word identification in the E and EAS conditions. The magnitude of improvement in the E condition was equivalent to that in the EAS condition. The improved performance was largely retained 1 month after training stopped. Conclusion: Auditory training, in the form administered in this study, can improve bimodal patients’ overall speech understanding by improving E-alone performance. The results of this study demonstrated that, on average, a phonemic-based auditory training resulted in a 10% improvement in vowel, consonant, and CNC word identification performance in the electric (E) and electric and acoustic stimulation (EAS) conditions for bimodal patients who had extensive experience (at least 2 years) with their cochlear implants and hearing aids. However, the auditory training, in a closed-set task, did not yield significant improvement in an open-set listening task (sentence identification) and two pitch-related listening tasks (voice gender and emotion identification). The magnitude of training benefit in the E condition was equivalent to that in the EAS condition, suggesting that the benefit was because of the central auditory learning effect for the electric signal but not the acoustic signal. The training benefit remained 1 month after training stopped. Although EAS benefit was not maximized by the training, auditory training, in the form administered in this study, can improve bimodal patients’ overall speech understanding by improving E-alone performance.