• Yang-Soo Yoon, Yongxin Li, Hou-Yong Kang, and Qian-Jie Fu.
• Communication and Neuroscience Division, House Ear Institute, 2100 West Third Street, Los Angeles, CA 90057, USA.
• Int J Audiol. 2011 Aug 1;50(8):554-65.

ObjectiveThe full benefit of bilateral cochlear implants may depend on the unilateral performance with each device, the speech materials, processing ability of the user, and/or the listening environment. In this study, bilateral and unilateral speech performances were evaluated in terms of recognition of phonemes and sentences presented in quiet or in noise.DesignSpeech recognition was measured for unilateral left, unilateral right, and bilateral listening conditions; speech and noise were presented at 0° azimuth. The 'binaural benefit' was defined as the difference between bilateral performance and unilateral performance with the better ear.Study SampleNine adults with bilateral cochlear implants participated.ResultsOn average, results showed a greater binaural benefit in noise than in quiet for all speech tests. More importantly, the binaural benefit was greater when unilateral performance was similar across ears. As the difference in unilateral performance between ears increased, the binaural advantage decreased; this functional relationship was observed across the different speech materials and noise levels even though there was substantial intra- and inter-subject variability.ConclusionsThe results indicate that subjects who show symmetry in speech recognition performance between implanted ears in general show a large binaural benefit.

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