Abstract
Objective: To study the development of the bilateral benefit in children using bilateral cochlear implants by measurements of speech recognition and sound localization. Design: Bilateral and unilateral speech recognition in quiet, in multi-source noise, and horizontal sound localization was measured at three occasions during a two-year period, without controlling for age or implant experience. Longitudinal and cross-sectional analyses were performed. Results were compared to cross-sectional data from children with normal hearing. Study sample: Seventy-eight children aged 5.1–11.9 years, with a mean bilateral cochlear implant experience of 3.3 years and a mean age of 7.8 years, at inclusion in the study. Thirty children with normal hearing aged 4.8–9.0 years provided normative data. Results: For children with cochlear implants, bilateral and unilateral speech recognition in quiet was comparable whereas a bilateral benefit for speech recognition in noise and sound localization was found at all three test occasions. Absolute performance was lower than in children with normal hearing. Early bilateral implantation facilitated sound localization. Conclusions: A bilateral benefit for speech recognition in noise and sound localization continues to exist over time for children with bilateral cochlear implants, but no relative improvement is found after three years of bilateral cochlear implant experience.
Acknowledgements
This work was funded by the Tysta Skolan Foundation and the regional agreement on medical training and clinical research (ALF) between Stockholm County Council and Karolinska Institutet, and Karolinska University Hospital. We are grateful for the participation of the children and their families in this study. We would like to acknowledge Eva Kindlundh, Erica Billermark, Birgitta Sköld, Dorotha Kuczynska, Johanna Åberg Clausen, Karl-Johan Lind, Katarina Svensson, and Eva Agelfors for support with measurements. The authors also thank Professor Mark Lutman, who developed and provided the localization test.
Declaration of interest: The authors report no conflicts of interest.