title: The addition of a contralateral microphone for unilateral cochlear implant users: not an alternative for bilateral cochlear implantation.
abstract: OBJECTIVE
  This study aimed to investigate whether unilateral cochlear implant (CI) users benefit from the addition of a contralateral microphone (CI-CROS) for spatial speech recognition.
  
  
  METHODS
  Tertiary referral otology and cochlear implant center.
  
  
  METHODS
  The digits-in-noise test was used to measure speech in noise recognition abilities. Evaluations were made in 3 conditions: speech and noise presented from the front of the listener (S0N0) and with spatial separation of speech and noise (S90N-90 and S-90N90). The performance of CI patients using CI-CROS was compared with their unilateral CI condition (n = 10), normal-hearing subjects (n = 12), and bilateral CI users (n = 5). The presence and extent of several binaural phenomena (binaural summation, binaural squelch, and the better-ear effect) were evaluated.
  
  
  RESULTS
  CI-CROS only provided a benefit in the listening situation wherein speech originates from the side of the CROS microphone; however, this benefit was repealed by disadvantages in other listening conditions. With CI-CROS, the hearing of patient is essentially monaural, albeit with bilateral input; therefore, patients were not able to benefit from the same binaural advantages as normal-hearing subjects and bilateral CI users. Moreover, patients using CI-CROS lost the ability to choose the optimal listening condition to perform as well as unilateral CI users.
  
  
  CONCLUSIONS
  We conclude that CI-CROS is not advisable for unilateral CI users. Bilateral cochlear implantation would be a better alternative for the rehabilitation of patients with unaidable hearing on the contralateral side.
authors.affiliation: Department of Otolaryngology-Head and Neck Surgery/Audiology and EMGO Institute for Health and Care Research, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Maarten C
authors.initials: MC
authors.lastname: van Loon
authors.forename: S Theo
authors.initials: ST
authors.lastname: Goverts
authors.forename: Paul
authors.initials: P
authors.lastname: Merkus
authors.forename: Erik F
authors.initials: EF
authors.lastname: Hensen
authors.forename: Cas
authors.initials: C
authors.lastname: Smits
mesh_terms: D000328:Adult; D000368:Aged; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D005260:Female; D006309:Hearing; D006320:Hearing Tests; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult