Using the observer-based psychophysical procedure to assess localization acuity in toddlers who use bilateral cochlear implants

HYPOTHESIS: Localization acuity will emerge in deaf children who receive bilateral cochlear implants (BI-CIs) before the age of 3 years but not in age-matched children who use a single device. BACKGROUND: There is a growing clinical trend in which infants with severe-to-profound sensorineural hearing loss are receiving BI-CIs by 3 years. Although there is general agreement that better communicative and educational outcomes are achieved when the first implant is provided at a young age, there are few behavioral data showing the functional benefits of providing infants with BI-CIs. One potential benefit of BI-CIs is improved localization acuity, which develops within the first few years of life. METHODS: Two groups of children with chronological ages ranging from 26 to 36 months participated: 1) children with normal hearing (n = 8) and 2) children with severe-to-profound sensorineural hearing loss (n = 18). Of the children who are deaf, 10 used BI-CIs, and 8 used unilateral cochlear implants. Localization acuity was measured with a single interval 2-alternative-forced choice right/left discrimination task, and minimum audible angles were computed at a performance level of 80% correct. Behavioral data were collected using the observer-based psychophysical procedure. RESULTS: Preliminary results show that the observer-based psychophysical procedure is a feasible method to measure localization acuity in children with normal hearing and in deaf children with cochlear implants and that localization acuity is emerging in toddlers with BI-CIs but not yet in toddlers with unilateral cochlear implants. CONCLUSION: These data are among the first to show localization acuity in young children who use BI-CIs.