title: Results from a psychoacoustic model-based strategy for the nucleus-24 and freedom cochlear implants.
abstract: OBJECTIVE
  In normal-hearing listeners acoustic masking occurs depending on frequency, amplitude, and energy of specific signals. If the selection of stimulated channels in cochlear implant systems was based on psychoacoustic masking models, the bandwidth of the electrode/nerve interface could be used more effectively by concentrating on relevant signal components and neglecting those that are usually not perceived by normal hearing listeners. Subsequently, a new strategy called PACE (Psychoacoustic Advanced Combination Encoder) has been developed which uses a psychoacoustic model for the channel selection instead of the simple maxima selection algorithm of the ACE strategy.
  
  
  METHODS
  Only subjects having at least 2 years experience with the ACE strategy were included. A counterbalanced cross-over design was used to compare the new speech coding strategy with the ACE strategy.
  
  
  METHODS
  The investigation was a prospective, within-subject, repeated-measures experiment.
  
  
  METHODS
  The study group consisted of 10 postlingually deafened adult subjects.
  
  
  METHODS
  The following programs were evaluated: (1) ACE with 8 maxima selected; (2) PACE with 8 channels selected; and (3) PACE with 4 channels selected.
  
  
  METHODS
  Speech perception tests in quiet and noise, Quality Assessment Questionnaire.
  
  
  RESULTS
  Results indicate a trend towards better performance with PACE. Scores in the Freiburg monosyllabic word test increased by 8% while the SNR50 in the Oldenburger sentence test improved significantly by 1.3 dB.
  
  
  CONCLUSIONS
  The use of psychoacoustic masking models in speech coding strategies has the potential to improve speech perception performance in cochlear implant subjects.
authors.affiliation: Department of Otolaryngology, Medical University of Hannover, Hannover, Germany. buechner@hoerzentrum-hannover.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Büchner
authors.forename: Waldo
authors.initials: W
authors.lastname: Nogueira
authors.forename: Bernd
authors.initials: B
authors.lastname: Edler
authors.forename: Rolf-Dieter
authors.initials: RD
authors.lastname: Battmer
authors.forename: Thomas
authors.initials: T
authors.lastname: Lenarz
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D002138:Calibration; D003054:Cochlear Implants / Q000706:statistics & numerical data*; D018592:Cross-Over Studies; D003638:Deafness / Q000523:psychology / Q000628:therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D015233:Models, Statistical; D018670:Monitoring, Ambulatory; D011571:Psychoacoustics; D013067:Speech Perception / Q000502:physiology