Binaural sensitivity in children with bilateral cochlear implants and in normal hearing children

Abstract

Children with bilateral cochlear implants (CIs), and normal hearing (NH) children were studied. One goal was to understand if sensitivity to interaural time difference (ITD) and interaural level difference (ILD) is attained at young ages with acoustic hearing. A second goal was to determine if children who hear through electrical stimulation of the auditory nerve are also sensitive to ITD and ILD cues. The bilaterally implanted children received stimulation through synchronized research processors, which is unlike the clinical speech processors that they use every day, which lack interaural synchronization. Sensitivity to ILDs was adult-like in NH children, and all children with CIs were able to use ILDs. Sensitivity to ITDs was, on average, adult-like in NH children, but many of the CI users were unable to use ITDs to determine if a sound was presented to the right or left. This contrasts with prior findings that children with CIs can detect the presence of a stimulus with a binaural cue, regardless of whether they could discriminate ITDs or not. Results underscore the importance of task selection in evaluating binaural sensitivity. Data are interpreted in the context of auditory plasticity and peripheral integrity for the development of binaural coding.