title: Speech Rate Normalization and Phonemic Boundary Perception in Cochlear-Implant Users.
abstract: Normal-hearing (NH) listeners rate normalize, temporarily remapping phonemic category boundaries to account for a talker's speech rate. It is unknown if adults who use auditory prostheses called cochlear implants (CI) can rate normalize, as CIs transmit degraded speech signals to the auditory nerve. Ineffective adjustment to rate information could explain some of the variability in this population's speech perception outcomes.
  
  
  
  Phonemes with manipulated voice-onset-time (VOT) durations were embedded in sentences with different speech rates. Twenty-three CI and 29 NH participants performed a phoneme identification task. NH participants heard the same unprocessed stimuli as the CI participants or stimuli degraded by a sine vocoder, simulating aspects of CI processing.
  
  
  
  CI participants showed larger rate normalization effects (6.6 ms) than the NH participants (3.7 ms) and had shallower (less reliable) category boundary slopes. NH participants showed similarly shallow slopes when presented acoustically degraded vocoded signals, but an equal or smaller rate effect in response to reductions in available spectral and temporal information.
  
  
  
  CI participants can rate normalize, despite their degraded speech input, and show a larger rate effect compared to NH participants. CI participants may particularly rely on rate normalization to better maintain perceptual constancy of the speech signal.
authors.affiliation: Department of Hearing and Speech Sciences, University of Maryland, College Park.
authors.forename: Brittany N
authors.initials: BN
authors.lastname: Jaekel
authors.affiliation: Department of Hearing and Speech Sciences, University of Maryland, College Park.
authors.forename: Rochelle S
authors.initials: RS
authors.lastname: Newman
authors.affiliation: Department of Hearing and Speech Sciences, University of Maryland, College Park.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Goupell
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D003054:Cochlear Implants; D003638:Deafness / Q000523:psychology / Q000534:rehabilitation*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010700:Phonetics; D011594:Psychometrics; D013018:Sound Spectrography; D013060:Speech; D013067:Speech Perception; D055815:Young Adult