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

Comparison between Bilateral Cochlear Implants and Neurelec Digisonict SP Binaural Cochlear Implant: Speech Perception, Sound Localization and Patient Self-Assessment

“…For spatial localization tasks, the performance measured in bilateral conditions is significantly better than that obtained in unilateral conditions, the average angular error measured by Litovsky et al [2009] being 28.4 versus 58.5°, respectively. Similar results were reported by Nava et al [2009].…”

Spatial hearing with a single cochlear implant in late-implanted adults

“…We found that the recipient with longer auditory experience (deafness onset when aged 39 years) recovered binaural sound localisation abilities shortly after implant activation (1 month), whereas the recipient with less auditory experience (deafness onset when aged 4 years) recovered binaural localisation abilities after 12 months from activation. Taken together, the results of the present work and the results of the previous study we conducted on bilateral CI recipients (Nava et al, 2009) lead to the prediction that whenever auditory cues are made available through the CI, postlingual recipients can rapidly re-weight previously learned auditory spatial mappings even after several years of sensory deprivation.…”

“…In the case of sequential bilateral CI recipients, any acquired monaural skill could somehow decrease due to the presence of the more used and potent binaural cue. For instance, we documented exactly this pattern of results in one bilateral CI recipient, tested longitudinally in a sound-source identification task (Nava et al, 2009). That recipient showed recovery of binaural spatial hearing, but at the same time lost the monaural abilities he had acquired in the previous 5 years of monaural experience.…”

“…Although the main aim of that study was to document binaural abilities in sequentially implanted patients, 2 participants out of 7 were also tested for their monaural localisation abilities prior to their second implantation. Both of these patients performed near chance with a single implant, but improved shortly after receiving the second CI (see also Nava et al, 2009 for similar evidence of fast acquisition of binaural spatial abilities after implantation of the second device). Dunn et al (2008) compared 12 bilateral CI users with 12 unilateral CI users (all postlingually deaf) and confirmed the better performance of the bilateral CIs group, whereas the single CI group performed near chance.…”

“…Such a difference could reflect the differential exposure to auditory cues to sound localisation in the two populations. Further evidence in support of the notion that the amount of exposure to auditory cues can constrain the time-course of acquisition of spatial abilities comes from a recent observation on two postlingual bilateral CI recipients, who had substantially different deafness onset (Nava et al, 2009). We found that the recipient with longer auditory experience (deafness onset when aged 39 years) recovered binaural sound localisation abilities shortly after implant activation (1 month), whereas the recipient with less auditory experience (deafness onset when aged 4 years) recovered binaural localisation abilities after 12 months from activation.…”