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The addition of a contralateral routing of signals microphone to a unilateral cochlear implant system—A prospective study in speech outcomes


  • The authors have no funding, financial relationships, or conflicts of interest to disclose.



The purpose of the study was to investigate the potential clinical advantages of incorporating a contralateral routing of signals (CROS) microphone in unilateral cochlear implant (CI) users.

Study Design:

A prospective study was undertaken on a group of 21 postlingually deafened adults who were all implanted with the same multichannel CI system.


Performance with a unilateral CI was compared with performance using both a unilateral implant and a CROS microphone system worn on the opposite site (CI-CROS). Speech understanding using the AzBio sentence was evaluated in quiet, with speech presented at 0° and 270° azimuth in the horizontal plane. Speech understanding in noise was performed with speech at 0°, and noise at 0°, 90°, and 270°.


A significant gain in speech understanding using CI-CROS compared to the unilateral CI alone was found in quiet when speech was presented at 270° (average improvement of 8.8%, P < .01). Participants also demonstrated statistically significant improvement using CI-CROS compared with the unilateral CI alone when noise was presented at 90° and speech at 0° (average improvement of 6.7%, P < .01).


Adding a contralateral microphone to a unilateral CI resulted in a significant improvement in speech understanding in different conditions. This method could provide a greater cost/benefit ratio than bilateral CIs and be a potential improvement for those who are not candidates for bilateral CIs. Laryngoscope, 2013

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