Changes in sound-source localization for children with bilateral severe to profound hearing loss following simultaneous bilateral cochlear implantation

Background: Sound localization is a valuable skill that children can develop to some extent via bilateral cochlear implants (biCIs). However, little is known regarding the change that can be expected in sound-source localization accuracy (SLA) pre- and post-biCI for children with bilateral, severe-to-profound hearing impairment who spent their early years listening via bilateral hearing aids (biHAs). This study therefore aimed to prospectively assess SLA in a group of children before, and at one year after, receiving simultaneous biCIs.

Methods: Ten children aged 5–18 years were tested. SLA was assessed using loudspeakers positioned at −60, −30, 0, +30, and +60 degrees azimuth. Root mean square (RMS) errors and percentage correct scores were calculated. Changes in SLA were analysed via paired t-tests and potential relationships between hearing threshold levels (HTLs) and SLA via correlation analyses. Response distributions via biHAs and biCIs were examined via scatterplots.

Results: The mean within-subject changes in SLA were a significant improvement in RMS error of 11.9° (p < 0.05) and in per cent correct by 21.5% (p < 0.05). Scatterplots demonstrated a trend towards better localization of sounds from 0° azimuth via biCIs compared to via biHAs. No significant associations were found between any measures of SLA and HTLs.

Conclusions: The findings of the present study demonstrate that simultaneous biCIs lead to improved sound localization in children with bilateral, severe to profound sensorineural hearing loss who previously used biHAs. SLA via biHAs or biCIs could not be predicted from children’s audiograms, and therefore should be measured directly.