title: Effects of talker variability on vowel recognition in cochlear implants.
abstract: OBJECTIVE
  To investigate the effects of talker variability on vowel recognition by cochlear implant (CI) users and by normal-hearing (NH) participants listening to 4-channel acoustic CI simulations.
  
  
  METHODS
  CI users were tested with their clinically assigned speech processors. For NH participants, 3 CI processors were simulated, using different combinations of carrier type and temporal envelope cutoff frequency (noise band/160 Hz, sine wave/160 Hz, and sine wave/20 Hz). Vowel recognition was measured for 4 talkers, presented in either a single-talker context (1 talker per test block) or a multi-talker context (4 talkers per test block).
  
  
  RESULTS
  CI users' vowel recognition was significantly poorer in the multi-talker context than in the single-talker context. When noise-band carriers were used in the simulations, NH performance was not significantly affected by talker variability. However, when sine-wave carriers were used in the simulations, NH performance was significantly affected by talker variability in both envelope filter conditions.
  
  
  CONCLUSIONS
  Because fundamental frequency was not preserved by the 20-Hz envelope filter and only partially preserved by the 160-Hz envelope filter, both spectral and temporal cues contributed to the talker variability effects observed with sine-wave carriers. Similarly, spectral and temporal cues may have contributed to the talker variability effects observed with CI participants.
authors.affiliation: University of Southern California, Los Angeles, USA. yipingch@usc.edu
authors.forename: Yi-ping
authors.initials: YP
authors.lastname: Chang
authors.forename: Qian-jie
authors.initials: QJ
authors.lastname: Fu
mesh_terms: D000328:Adult; D000368:Aged; D003054:Cochlear Implants; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010700:Phonetics; D021641:Recognition, Psychology; D013063:Speech Discrimination Tests; D013067:Speech Perception; D014705:Verbal Behavior