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CNI Center for Hearing
Research & Outcomes
Research
Cochlear implant technology is under constant improvements and the CNI Center for Hearing is very involved in cochlear implant research. CNI's member physicians continue to participate in numerous FDA clinical trials. Our patients are assured to receive the most up-to-date technology. The center’s commitment to research is strong, and this will continue well into the future.
Publications
Analysis and Focus of Intracochlear Stimulation
-Presented at the 12th International Conference on Cochlear Implants in Children
-6/17/2009-6/20/2009, Seattle, Washington
Zachary M. Smith1, Christopher J. Long1, Chris van den Honert1, Donald K. Eddington2, Tim A. Holden3, Clough Shelton4, David C. Kelsall5
1Research and Applications, Cochlear Ltd, Centennial, CO, USA
2Massachusetts Eye & Ear Infirmary, Boston, MA, USA
3Washington University School of Medicine, St. Louis, MO, USA
4Dept. of Otolaryngology, University of Utah, Salt Lake City, UT, USA
5CNI Rocky Mountain Cochlear Implant Center, Englewood, CO, USA
At CIAP 2007 we argued that channel-specific temporal fine structure in the neural response to electric stimulation cannot be controlled with monopolar channels. Due to spatial spread of excitation, any given auditory neuron inevitably responds to stimuli from multiple channels. Thus the intended temporal patterning is smeared and corrupted in the activity of the target neurons. In order to address this problem we described a method for focusing intracochlear stimulation using multipolar phased array (PA) channels. We presented evidence that simultaneous interactions among PA channels are substantially weaker than those of monopolar channels. We also speculated that variations in PA threshold across cochlear place might reflect neuronal degeneration patterns.
Standard PA channel weights theoretically achieve optimal focusing of the potential field within scala tympani (ST). However analytic studies have shown that extrapolation errors in some of the transimpedance values that are used to compute the standard weights can compromise focusing in ST. Modeling of intracochlear current flow with PA stimulation further suggests that optimal focusing of the potential field in ST leads to suboptimal focusing of radial current within Rosenthal’s canal. Parallel psychophysical studies have demonstrated that simultaneous channel interactions with PA stimulation can be further reduced by iteratively adjusting the channel weights in systematic ways. CT scan data have been used to estimate modiolar proximity of electrode contacts as a function of cochlear place. These studies show that a substantial part of the variance of PA thresholds across place is accounted for by modiolar proximity.
Results of these studies and their implications of these findings will be discussed.
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Impact of Age at Second Implant on Speech Perception in Noise
-Presented at the 12th International Conference on Cochlear Implants in Children
-6/17/2009-6/20/2009, Seattle, Washington
Allison M. Biever, Au.D. and David C. Kelsall, M.D.
This prospective study examines the BKB-SIN scores of 40 children (aged 4 to 17) who received a sequential bilateral cochlear implant. The mean time between cochlear implant surgeries was 5.6 years. BKB-SIN scores were analyzed as a function of the child’s age at the time of the second implant. BKB-SIN tasks were administered to the pediatric bilateral recipients after 6 months to 4 years of device experience with the second implant. BKB-SIN scores for these three groups were reported for the original ear only, the second ear only, and in the binaural condition. Individual data suggest that speech reception thresholds (BKB-SIN) were superior for younger children. Regardless of age group, the trend was for attainment of better speech reception scores in the first ear implanted compared with the second ear, even in children with more than 12 months of device use. Group data indicate that bilateral speech reception thresholds (BKB-SIN) for bilateral cochlear implant recipients are superior to thresholds obtained with first or second implant alone.
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