Cortical Processing of Vocal and Nonvocal Sounds in Cochlear-Implanted Children: An Electrophysiological Study

Objectives: For prelingually deaf children, cochlear implants (CIs) can
restore auditory input to the auditory cortex and the ability to acquire
spoken language. Language development is strongly intertwined with
voice perception. The aim of this electrophysiological study was to
investigate human voice processing using measures of cortical auditory
evoked potentials (AEPs) in pediatric CI users.
Design: Cortical AEPs were measured in 8 CI children (4 to 12 years old)
with good auditory and language performance and 8 normal-hearing
(NH) age-matched controls. The auditory stimuli were nonspeech vocal
sounds (laughing, sighing, coughing) and environmental sounds (e.g.,
telephones, alarms, cars, bells, water, wind). Independent component
analysis was used to minimize the CI artifact in cortical AEPs.
Results: Fronto-temporal positivity to vocal sounds was found in NH
children, with a significant effect in the 140 to 240 msec latency range.
In CI children, there was a positive response to vocal sounds in the 170
to 250 msec latency range, with a more diffuse and anterior distribution
than in the NH children.
Conclusions: Cortical responses to vocal sounds were recorded in CI
children. The topography and latency of response to voice differed from
that of NH children. The results suggest that cortical reorganization for
processing vocal sounds may occur in congenitally deaf children fitted
with a CI.