Does matching stimulation rates in bilateral cochlear implants (CI) really matter? When bilateral CI recipients are implanted sequentially, the first implant is likely to be mapped at a relatively slow stimulation rate, while the second may be capable of faster stimulation rates, due to the technology available at implantation. Ten sequential bilateral CI recipients were used to investigate this question. Prior to the experiment, all participants used slow rates in the first CI, ranging from 720-1856 Hz. Five used slow rates (900Hz) (matched) on the second CI, and five used high rates (2400-3867Hz) (mismatched). The stimulation rate in the first implanted CI was never changed (non-modified), but all participants were given at least four weeks experience with both low and high rates on the newer implant.
Speech perception in quiet (CNC) and in noise (CRISP) with the first CI alone (non-modified), the second CI alone (modified), and bilaterally was evaluated four times during the experiment. Phase 1) Baseline testing was conducted prior to any re-programming. The second implant was re-mapped with either a slow or high rate. Phase 2) Participants were tested and re-mapped with the alternative rate after four weeks experience with the new map. Phase 3) After four weeks experience with the alternative map, participants were retested then re-mapped with the original rates. Phase 4) Participants were given one week of additional experience before final testing. Participants were asked which mapping configuration they preferred and would like to continue using. Most (8/10) participants choose to leave with the mismatched configuration.
With bilateral stimulation, speech perception was better listening in quiet when they used a higher stimulation rate in one ear and a slow rate in the other ear than when they used slow rates in both ears, regardless of the program used before entering the study. There was no significant improvement in the CRISP (independent of noise source location) when participants were using both rate configurations with the modified CI alone, non-modified CI alone, or bilateral CIs. Clinicians programming bilateral CI patients who have internal equipment with different capabilities may find this information helpful when mapping this population.
|Advisor:||Long, Glenis R.|
|Commitee:||Litovsky, Ruth, Svirsky, Mario|
|School:||City University of New York|
|Department:||Speech & Hearing Sciences|
|School Location:||United States -- New York|
|Source:||DAI-B 74/09(E), Dissertation Abstracts International|
|Subjects:||Audiology, Speech therapy|
|Keywords:||Bilateral cochlear implants, Cochlear implants, Speech perception, Stimulation rate|
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