gms | German Medical Science

Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants

Medical University of Hannover

01.06. bis 04.06.2005, Hannover

Impedances and program parameters of HiRes strategy users

Meeting Abstract

  • corresponding author F. Vanpoucke - Medical Electronics Laboratory, University of Antwerp, Belgium
  • C. Frohne-Büchner - Research Europe, Advanced Bionics
  • R.D. Battmer - ENT Department, Medizinische Hochschule Hannover, Germany
  • T. Lenarz - ENT Department, Medizinische Hochschule Hannover, Germany

Medical University of Hannover, Department of Otolaryngology. Fourth International Symposium and Workshops: Objective Measures in Cochlear Implants. Hannover, 01.-04.06.2005. Düsseldorf, Köln: German Medical Science; 2005. Doc05omci093

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Veröffentlicht: 31. Mai 2005

© 2005 Vanpoucke et al.
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To collect normative field data for the variation of electrode impedances and program parameters over a large group of subjects, wearing either an Advanced Bionics CII or HR90k cochlear implant and fitted with the SoundWave software.

Materials and Methods

For 184 subjects the impedance and program records were extracted from the SoundWave database, totaling 196 ears, 89 of which are implanted with a CII device and 107 with a HR90k device. For these ears a total of 1315 impedance records were available. Only HiResolution programs that were downloaded into the first slot in the processor were considered, in total 620 records, as these programs were most likely used in daily listening situations. Histograms were computed for the electrode impedance and stimulation rate, pulse width and most comfortable level. To obtain an insight in the typical shape of the most comfortable levels, a principal component analysis was performed.


The following statistics were obtained, denoted as {average value, standard deviation, median value}.

• electrode impedance {7.3, 3.9,6.7} kΩ.

• program parameters

•• In 95% of the programs the HiRes-S strategy was used. The remaining part implemented the HiRes-P strategy.

•• Repetition rate {2400,1052,2486} pulses per second per channel

•• Phase duration {18.6, 12.0, 12.6} µs.

•• Most comfortable level {800, 331, 753} µA

•• Injected charge {13.5,7.9,11.6} nC or {173,101,148} CU

The variability on all parameters is quite large, and cannot be easily explained by a limited number of factors.

The principal component analysis of the M-levels shows a dominant almost horizontal component. The second component is a linear slope. Higher components introduce curvature as they resemble a half-period and full-period of a sine. Therefore, the average SoundWave M-level profiles can be well approximated with a level and a slope.