Bilateral Cochlear Implants in Adults and Children

Objective: To measure the benefit (ie, sound localization and speech intelligibility in noise) of bilateral cochlear implants (CIs) in adults and in children.

Design, Setting, And Patients: Seventeen adults and 3 children underwent testing 3 months after activation of bilateral hearing. Adults received their devices in a simultaneous procedure and children in sequential procedures (3-8 years apart). Adults underwent testing of sound localization and speech intelligibility, with a single CI and bilaterally. Children underwent testing of sound localization, right/left discrimination, and speech intelligibility, with the first CI alone and bilaterally. We used computer games to attract the children's attention and engage them in the psychophysical tasks for long periods of time.

Results: Preliminary findings suggest that, for adults, bilateral hearing leads to better performance on the localization task, and on the speech task when the noise is near the poorer of the 2 ears. In children, localization and discrimination are slightly better under bilateral conditions, but not remarkably so. On the speech tasks, 1 child did not benefit from bilateral hearing. Two children showed consistent improvement with bilateral hearing when the noise was near the side that underwent implantation first.

Conclusions: Bilateral CIs may offer advantages to some listeners. The tasks described in this study might offer a powerful tool for measuring such advantages, especially in young children. The extent of the advantage, however, is difficult to ascertain after 3 months of bilateral listening experience, and might require a more prolonged period of adjustment and learning. Future work should be aimed at examining these issues.