title: Multicenter U.S. bilateral MED-EL cochlear implantation study: speech perception over the first year of use.
abstract: OBJECTIVE
  Binaural hearing has been shown to support better speech perception in normal-hearing listeners than can be achieved with monaural stimulus presentation, particularly under noisy listening conditions. The purpose of this study was to evaluate whether bilateral electrical stimulation could confer similar benefits for cochlear implant listeners.
  
  
  METHODS
  A total of 26 postlingually deafened adult patients with short duration of deafness were implanted at five centers and followed up for 1 yr. Subjects received MED-EL COMBI 40+ devices bilaterally; in all but one case, implantation was performed in a single-stage surgery. Speech perception testing included CNC words in quiet and CUNY sentences in noise. Target speech was presented at the midline (0 degrees), and masking noise, when present, was presented at one of three simulated source locations along the azimuth (-90, 0, and +90 degrees).
  
  
  RESULTS
  Benefits of bilateral electrical stimulation were observed under conditions in which the speech and masker were spatially coincident and conditions in which they were spatially separated. Both the "head shadow" and "summation" effects were evident from the outset. Benefits consistent with "binaural squelch" were not reliably observed until 1 yr after implantation.
  
  
  CONCLUSIONS
  These results support a growing consensus that bilateral implantation provides functional benefits beyond those of unilateral implantation. Longitudinal data suggest that some aspects of binaural processing continue to develop up to 1 yr after implantation. The squelch effect, often reported as absent or rare in previous studies of bilateral cochlear implantation, was present for most subjects at the 1 yr measurement interval.
authors: Department of Otolaryngology/Head and Neck Surgery, University of North Carolina School of Medicine, Chapel Hill, North Carolina 27599, USA. ebuss@med.unc.edu
authors: Emily
authors: E
authors: Buss
authors: Harold C
authors: HC
authors: Pillsbury
authors: Craig A
authors: CA
authors: Buchman
authors: Carol H
authors: CH
authors: Pillsbury
authors: Marcia S
authors: MS
authors: Clark
authors: David S
authors: DS
authors: Haynes
authors: Robert F
authors: RF
authors: Labadie
authors: Susan
authors: S
authors: Amberg
authors: Peter S
authors: PS
authors: Roland
authors: Pamela
authors: P
authors: Kruger
authors: Michael A
authors: MA
authors: Novak
authors: Julie A
authors: JA
authors: Wirth
authors: Jennifer M
authors: JM
authors: Black
authors: Robert
authors: R
authors: Peters
authors: Jennifer
authors: J
authors: Lake
authors: P Ashley
authors: PA
authors: Wackym
authors: Jill B
authors: JB
authors: Firszt
authors: Blake S
authors: BS
authors: Wilson
authors: Dewey T
authors: DT
authors: Lawson
authors: Reinhold
authors: R
authors: Schatzer
authors: Patrick S C
authors: PS
authors: D'Haese
authors: Amy L
authors: AL
authors: Barco
mesh_terms: D000328:Adult; D000368:Aged; D019929:Cochlear Implantation; D003638:Deafness / Q000601:surgery*; D004558:Electric Stimulation / Q000295:instrumentation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D013067:Speech Perception / Q000502:physiology*; D013997:Time Factors; D014825:Vocabulary