title: The relationship between binaural benefit and difference in unilateral speech recognition performance for bilateral cochlear implant users.
abstract: OBJECTIVE
  The 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.
  
  
  METHODS
  Speech 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.
  
  
  METHODS
  Nine adults with bilateral cochlear implants participated.
  
  
  RESULTS
  On 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.
  
  
  CONCLUSIONS
  The results indicate that subjects who show symmetry in speech recognition performance between implanted ears in general show a large binaural benefit.
authors.affiliation: Communication and Neuroscience Division, House Ear Institute, 2100 West Third Street, Los Angeles, CA 90057, USA.
authors.forename: Yang-Soo
authors.initials: YS
authors.lastname: Yoon
authors.forename: Yongxin
authors.initials: Y
authors.lastname: Li
authors.forename: Hou-Yong
authors.initials: HY
authors.lastname: Kang
authors.forename: Qian-Jie
authors.initials: QJ
authors.lastname: Fu
mesh_terms: D000161:Acoustic Stimulation; D000368:Aged; D000369:Aged, 80 and over; D019929:Cochlear Implantation / Q000295:instrumentation*; D003054:Cochlear Implants; D012048:Correction of Hearing Impairment / Q000523:psychology*; D005260:Female; D007839:Functional Laterality; D034381:Hearing Loss / Q000523:psychology / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009622:Noise / Q000009:adverse effects; D010470:Perceptual Masking; D019986:Persons with Hearing Disabilities / Q000523:psychology / Q000534:rehabilitation*; D011474:Prosthesis Design; D021641:Recognition, Psychology; D013061:Speech Acoustics; D013063:Speech Discrimination Tests; D013065:Speech Intelligibility; D013067:Speech Perception; D013069:Speech Reception Threshold Test; D055815:Young Adult