Document Detail

Benefit of high-rate envelope cues in vocoder processing: effect of number of channels and spectral region.
MedLine Citation:
PMID:  19062865     Owner:  NLM     Status:  MEDLINE    
In cochlear implants, or vocoder simulations of cochlear implants, the transmission of envelope cues at high rates (related to voice fundamental frequency, f0) may be limited by the widths of the filters used to form the channels and/or by the cutoff frequency, f(lp), of the low-pass filters used for envelope extraction. The effect of varying f(lp) in tone and noise vocoders was investigated for channel numbers, N, from 6 to 18. As N increased, the widths of the channels decreased. The value of f(lp) was 45 Hz (envelope or "E" filter), or 180 Hz (pitch or "P" filter). The following combinations of cutoff frequencies were used for channels below and above 1500 Hz, respectively: EE, PE, EP, and PP. Results from a competing-talker task showed that the tone vocoder led to better intelligibility than the noise vocoder. The PP condition led to the best intelligibility and the EE condition to the worst. For N=6, intelligibility was better for condition PE than for condition EP. For N=18, the reverse was true. The results indicate that the channel bandwidths can compromise the transmission of f0-related envelope information, and suggest that vocoder simulations of cochlear-implant processing have limitations.
Michael A Stone; Christian Füllgrabe; Brian C J Moore
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of the Acoustical Society of America     Volume:  124     ISSN:  1520-8524     ISO Abbreviation:  J. Acoust. Soc. Am.     Publication Date:  2008 Oct 
Date Detail:
Created Date:  2008-12-09     Completed Date:  2009-03-05     Revised Date:  2014-02-19    
Medline Journal Info:
Nlm Unique ID:  7503051     Medline TA:  J Acoust Soc Am     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2272-82     Citation Subset:  IM    
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MeSH Terms
Acoustic Stimulation
Audiometry, Speech
Auditory Threshold
Cochlear Implants*
Computer Simulation*
Perceptual Masking*
Prosthesis Design
Reproducibility of Results
Signal Processing, Computer-Assisted*
Speech Acoustics
Speech Intelligibility*
Young Adult
Grant Support
G8717539//Medical Research Council

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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