Document Detail


Combined effects of frequency compression-expansion and shift on speech recognition.
MedLine Citation:
PMID:  17485977     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: To explore combined acute effects of frequency shift and compression-expansion on speech recognition, using noiseband vocoder processing. DESIGN: Recognition of vowels and consonants, processed with a noiseband vocoder, was measured with five normal-hearing subjects, between the ages of 27 and 35 yr. The speech signal was filtered into 8 or 16 analysis bands and the envelopes were extracted from each band. The carrier noise bands were modulated by the envelopes and resynthesized to produce the processed speech. In the baseline matched condition, the frequency ranges of the corresponding analysis and carrier bands were the same. In the shift only condition, the frequency ranges of the carrier bands were shifted up or down relative to the analysis bands. In the compression and expansion only conditions, the analysis band range was made larger or smaller, respectively, than the carrier band range. By applying the shift to carrier bands and compression or expansion to analysis bands simultaneously, the combined effects of the two spectral distortions on speech recognition were explored. RESULTS: When the spectral distortions of compression-expansion or shift were applied separately, the performance was reduced from the baseline matched condition. However, when the two spectral degradations were applied simultaneously, a compensatory effect was observed; the reduction in performance was smaller for some combinations compared to the reduction observed for each distortion individually. CONCLUSIONS: The results of the present study are consistent with previous vocoder studies with normal-hearing subjects that showed a negative effect of spectral mismatch between analysis and carrier bands on speech recognition. The present results further show that matching the frequency ranges of 1 to 2 kHz, which contain important speech information, can be more beneficial for speech recognition than matching the overall frequency ranges, in certain conditions.
Authors:
Deniz Başkent; Robert V Shannon
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Ear and hearing     Volume:  28     ISSN:  0196-0202     ISO Abbreviation:  Ear Hear     Publication Date:  2007 Jun 
Date Detail:
Created Date:  2007-05-08     Completed Date:  2007-07-10     Revised Date:  2007-12-03    
Medline Journal Info:
Nlm Unique ID:  8005585     Medline TA:  Ear Hear     Country:  United States    
Other Details:
Languages:  eng     Pagination:  277-89     Citation Subset:  IM    
Affiliation:
Department of Biomedical Engineering, University of Southern California, Los Angeles, USA. deniz_baskent@starkey.com
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MeSH Terms
Descriptor/Qualifier:
Adult
Audiometry / instrumentation*
Cochlear Implants
Female
Hearing Aids
Hearing Disorders / therapy
Humans
Male
Noise
Phonetics*
Recognition (Psychology)*
Speech Perception*
Grant Support
ID/Acronym/Agency:
N01-DC-92100/DC/NIDCD NIH HHS; R01-DC-01526/DC/NIDCD NIH HHS

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


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