Benefits of bilateral cochlear implantation: a review.
OBJECTIVE
Although unilateral cochlear implantation generally provides good speech understanding under quiet conditions, cochlear implantation patients frequently report difficulty understanding speech when exposed to background noise and with sound localization. Since these two listening functions require binaural stimulation for normal individuals and hearing aid recipients, it is not surprising that there is growing interest in binaural implants. This update reviews the basics of binaural listening and the advantages and disadvantages of binaural cochlear implantation.


RESULTS
Although the psychoacoustic literature has long demonstrated the benefits of binaural hearing, only recently have studies shown improvement in speech intelligibility with bilateral implants compared with unilateral implants. Of the three known binaural mechanisms, the head shadow effect provides greater benefit than binaural squelch or summation. In addition, binaural cochlear implants improve the ability to localize sound.


CONCLUSIONS
Bilateral implantation provides multiple benefits to patients with severe to profound hearing loss. Research is currently directed at improving speech intelligibility by utilizing evolving technologies in speech-processing strategies.
Brown
Kevin D
KD
Department of Otolaryngology, University of Miami Ear Institute, Miami, Florida 33101, USA.
Balkany
Thomas J
TJ
D001307:Auditory Perception; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003638:Deafness / Q000601:surgery*; D006801:Humans; D013065:Speech Intelligibility