Hearing again with two ears: recovery of spatial hearing after bilateral cochlear implantation.

Bilateral cochlear implants (CI) offer a unique opportunity for the study of spatial hearing plasticity in humans. Here we studied the recovery of spatial hearing in two sequential bilateral CI recipients, adopting a longitudinal approach. Each recipient was tested in a sound-source identification task shortly after bilateral activation and at 1, 6, and 12 months follow-up. The results show fast recovery (1 month from CI activation) in the recipient who had substantial experience with auditory cues in adulthood. By contrast, the bilateral CI recipient who developed profound deafness in childhood, regained spatial hearing abilities only 12 months after CI activation. These findings provide the first direct evidence that recovery of auditory spatial abilities in bilateral CI recipients can occur shortly after activation of the two devices. In addition, they suggest that previous auditory experience can constrain the time course of this recovery.