Clinical Research Studies

Prior to the onset of deafness, the auditory brain of post-lingually deafened adults develops in response to a rich complement of spectral, temporal, and intensity cues from acoustic input. After becoming deaf and subsequently receiving a cochlear implant (CI), these recipients need time to adjust to the CI but eventually attain relatively high levels of speech understanding. By contrast, the auditory brain of children who are born deaf and receive a CI develops in direct response to electrical stimulation. Although their auditory systems do not benefit from the same rich acoustic input as that of post-lingually deafened adults prior to deafness, children have the advantage of adapting to the CI during the time window when neural plasticity is most sensitive. Therefore, it is assumed that the auditory brains of these two populations are different—yet both groups are fitted with the same coding strategies that were developed primarily for post-lingually deafened adults without consideration of children’s select listening needs. Although many implanted children do develop speech recognition (e.g. Niparko et al., 2010; Eisenberg et al., 2016) outcome variability remains high. Evidence from a small group of children with single-channel CIs (Berliner et al., 1989) suggests that early deafened children are able to access temporal cues from electrical stimulaton to understand speech in an open set. Pilot data from the Landsberger lab suggest that children with multichannel CIs attain better modulation detection thresholds than adult CI recipients. We recently published that early deafened children are less able to access spectral cues from multichannel CIs to the same extent as post-lingually deafened adults and hearing children (Landsberger et al., 2017). Taken together, these findings imply that early implanted children develop auditory skills differently than implanted adults through differential weighting of cues or combinations of cues. If so, then establishing optimal CI programming strategies, such as adjusting amplitude mapping to maintain key spectro-temporal contrasts, could conceivably improve perceptual outcomes for early implanted children.