Bilateral versus unilateral cochlear implants in children: Speech recognition, sound localization, and parental reports

Abstract

Objective: To compare bilateral and unilateral speech recognition in quiet and in multi-source noise, and horizontal sound localization of low and high frequency sounds in children with bilateral cochlear implants. Design: Bilateral performance was compared to performance of the implanted side with the best monaural speech recognition in quiet result. Parental reports were collected in a questionnaire. Results from the CI children were compared to binaural and monaural performance of normal-hearing peers. Study sample: Sixty-four children aged 5.1–11.9 years who were daily users of bilateral cochlear implants. Thirty normal-hearing children aged 4.8–9.0 years were recruited as controls. Results and Conclusions: Group data showed a statistically significant bilateral speech recognition and sound localization benefit, both behaviorally and in parental reports. The bilateral speech recognition benefit was smaller in quiet than in noise. The majority of subjects localized high and low frequency sounds significantly better than chance using bilateral implants, while localization accuracy was close to chance using unilateral implants. Binaural normal-hearing performance was better than bilateral performance in implanted children across tests, while bilaterally implanted children showed better localization than normal-hearing children under acute monaural conditions.

Key Words::

• Bilateral cochlear implants
• children
• release from masking
• sound localization
• parental reports

Acknowledgements

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, Martin Eklöf for help with graphics, and Erik Berninger for fruitful discussions on the data analysis. This work has been presented in part as an oral paper at the 12th International Symposium on Cochlear Implants in Children, Seattle, USA, June 2009, and as an oral paper at the 9th European Symposium on Pediatric Cochlear Implantation, Warsaw, Poland, May 2009.

Declaration of interest: The authors report no declarations of interest.

This work was partly funded by ALF grants from Stockholm City Council.