Artikel
Improved Frequency Resolution by Virtual Channels in the HiRes System
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Autoren
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Martina Brendel
- Medical University of Hannover, Department of Otolaryngology, Hannover
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Corinna Habermann
- Medical University of Hannover, Department of Otolaryngology, Hannover
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Andreas Buechner
- Medical University of Hannover, Department of Otolaryngology, Hannover
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Carolin Frohne-Buechner
- Medical University of Hannover, Advanced Bionics GmbH, Hannover
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Timo Stoever
- Medical University of Hannover, Department of Otolaryngology, Hannover
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Thomas Lenarz
- Medical University of Hannover, Department of Otolaryngology, Hannover
| Veröffentlicht: | 22. September 2005 |
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Gliederung
Text
As shown in the clinical routine the majority of the CI users is able to distinguish the pitch of two adjacent channels. The main question of this study is, whether the participants are able to discriminate frequencies between these physical channels.
To create additional frequency percepts, the so called “virtual channels”, a special technique is used which distributes the stimulating current to two neighboured electrode contacts (“current steering”).
In this study 50 adult CI users participated with an averaged age of 48 years. All participants use the CII or the HiRes90K implant system and the HiRes speech coding strategy.
During the measurement with a combination of physical and intermediate channels, the CI user has to listen to two stimuli with different current distribution between adjacent contacts. Afterwards he has to decide which tone the higher one was, or whether they have the same pitch. The pitch ranking measurement was performed once in an acute test session. In a subgroup the measurement has been repeated during the first fitting phase, after one month, after three months and six months to evaluate a possible learning progress.
80 % of the participants are able to distinguish intermediate channels, 16 % are able to distinguish 8 intermediate channels, which correlates to the half of physical channels. The majority of users has poorer pitch resolution in the basal part than in the medial and apical.
As virtual channels were perceived by the majority of CI users there is a potential for the development of advanced speech coding strategies providing improved spectral resolution.
