Skip to content


  • Research Article
  • Open Access

A Psychoacoustic "NofM"-Type Speech Coding Strategy for Cochlear Implants

  • 1Email author,
  • 2,
  • 2 and
  • 1
EURASIP Journal on Advances in Signal Processing20052005:101672

  • Received: 1 June 2004
  • Published:


We describe a new signal processing technique for cochlear implants using a psychoacoustic-masking model. The technique is based on the principle of a so-called "NofM" strategy. These strategies stimulate fewer channels ( ) per cycle than active electrodes (NofM; ). In "NofM" strategies such as ACE or SPEAK, only the channels with higher amplitudes are stimulated. The new strategy is based on the ACE strategy but uses a psychoacoustic-masking model in order to determine the essential components of any given audio signal. This new strategy was tested on device users in an acute study, with either 4 or 8 channels stimulated per cycle. For the first condition (4 channels), the mean improvement over the ACE strategy was . For the second condition (8 channels), no significant difference was found between the two strategies.

Keywords and phrases:

  • cochlear implant
  • NofM
  • ACE
  • speech coding
  • psychoacoustic model
  • masking

Authors’ Affiliations

Laboratorium für Informationstechnologie, Universität Hannover, Schneiderberg 32, Hannover, 30167, Germany
Department of Otolaryngology, Medical University Hanover, Carl-Neuberg-Strasse 1, Hannover, 30625, Germany


© Waldo Nogueira et al. 2005

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.