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  • Research Article
  • Open Access

A Two-Microphone Noise Reduction System for Cochlear Implant Users with Nearby Microphones—Part I: Signal Processing Algorithm Design and Development

  • 1Email author,
  • 1, 2,
  • 3 and
  • 4
EURASIP Journal on Advances in Signal Processing20082008:647502

  • Received: 27 November 2007
  • Accepted: 20 March 2008
  • Published:


Users of cochlear implant systems, that is, of auditory aids which stimulate the auditory nerve at the cochlea electrically, often complain about poor speech understanding in noisy environments. Despite the proven advantages of multimicrophone directional noise reduction systems for conventional hearing aids, only one major manufacturer has so far implemented such a system in a product, presumably because of the added power consumption and size. We present a physically small (intermicrophone distance 7 mm) and computationally inexpensive adaptive noise reduction system suitable for behind-the-ear cochlear implant speech processors. Supporting algorithms, which allow the adjustment of the opening angle and the maximum noise suppression, are proposed and evaluated. A portable real-time device for test in real acoustic environments is presented.


  • Cochlear Implant
  • Cochlear Implant User
  • Adaptive Noise
  • Speech Understanding
  • Speech Processor

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Authors’ Affiliations

Department of ENT, Head and Neck Surgery Inselspital, University of Berne, CH-3010 Berne, Switzerland
Bernafon Inc., Berne, CH-3018 Berne, Switzerland
Laboratoire des Microprocesseurs, Ecole d'Ingénieurs de Genève, 1202 Geneva, Switzerland
Clinique O.R.L., Hôpital Universitaire de Genève, 1211 Geneva, Switzerland


© Martin Kompis et al. 2008

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.