title: Shifting Fundamental Frequency in Simulated Electric-Acoustic Listening: Effects of F0 Variation.
abstract: OBJECTIVE
  Shifting the mean fundamental frequency (F0) of target speech down in frequency may be a way to provide the benefits of electric-acoustic stimulation (EAS) to cochlear implant (CI) users whose limited residual hearing precludes a benefit typically, even with amplification. However, previous study showed a decline in the amount of benefit at the greatest downward frequency shifts, and the authors hypothesized that this might be related to F0 variation. Thus, in the present study, the authors sought to determine the relationship between mean F0, F0 variation, and the benefits of combining electric stimulation from a CI with low-frequency residual acoustic hearing.
  
  
  METHODS
  The authors measured speech intelligibility in normal-hearing listeners using an EAS simulation consisting of a sine vocoder combined either with speech low-pass filtered at 500 Hz, or with a pure tone representing target F0. The authors used extracted target voice pitch information to modulate the tone, and manipulated both the frequency of the carrier (mean F0), as well as the standard deviation of the voice pitch information (F0 variation).
  
  
  RESULTS
  A decline in EAS benefit was observed at the lowest mean F0 tested, but this decline disappeared when F0 variation was reduced to be proportional to the amount of the shift in frequency (i.e., when F0 was shifted logarithmically instead of linearly).
  
  
  CONCLUSIONS
  Lowering mean F0 by shifting the frequency of a pure tone carrying target voice pitch information can provide as much EAS benefit as an unshifted tone, at least in the current simulation of EAS. These results may have implications for CI users with extremely limited residual acoustic hearing.
authors.affiliation: 1Psychoacoustics Laboratory, Department of Communication Science and Disorders, The University of Pittsburgh, Pittsburgh, Pennsylvania, USA; 2Psychoacoustics Laboratory, Department of Speech and Hearing Science, Arizona State University, Tempe, Arizona, USA; and 3Speech Psychoacoustics Lab, Department of Speech and Hearing Science, The Ohio State University, Columbus, Ohio, USA.
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Brown
authors.forename: Kate
authors.initials: K
authors.lastname: Helms Tillery
authors.forename: Frédéric
authors.initials: F
authors.lastname: Apoux
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Doyle
authors.forename: Sid P
authors.initials: SP
authors.lastname: Bacon
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods*; D000328:Adult; D019929:Cochlear Implantation; D003054:Cochlear Implants; D003638:Deafness / Q000534:rehabilitation*; D004558:Electric Stimulation / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D010898:Pitch Perception; D013067:Speech Perception; D055815:Young Adult