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Using the Observer-Based Psychophysical Procedure to Assess Localization Acuity in Toddlers Who Use Bilateral Cochlear Implants

Grieco-Calub, Tina M.*; Litovsky, Ruth Y.; Werner, Lynne A.

doi: 10.1097/mao.0b013e31816250fe
Original Articles

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.

*Waisman Center, †Department of Communicative Disorders and Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin; and ‡Department of Speech and Hearing Sciences, University of Washington, Seattle, Washington, U.S.A.

Address correspondence and reprint requests to Tina M. Grieco-Calub, Ph.D., Waisman Center, University of Wisconsin-Madison, 1500 Highland Ave, Room 565, Madison, WI 53705; E-mail:

This study was supported by NIH NIDCD R21DC006642 (R. Y. L.), NIH NIDCD F32DC008452 (T. M. G.-C.), Cochlear Americas for sponsoring participation of a subset of children with cochlear implants.

Financial Disclosure: In the past year, Dr. Ruth Livotsky has served as a paid consultant to Cochlear America and was reimbursed for time spent on a speaking engagement and preparing a "white paper."

© 2008 Otology & Neurotology, Inc.