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Comodulation masking release with signal-masker interactions represented in the envelope.
MedLine Citation:
PMID:  20330301     Owner:  NLM     Status:  In-Data-Review    
Abstract/OtherAbstract:
In normal hearing, the threshold of a tone masked by a modulated narrow-band on-frequency masker (OFB) can be reduced if correlated modulation is present on spectrally distant flanking bands (FBs), an effect known as comodulation masking release (CMR). Since electric hearing with current cochlear implants is based on envelope information, comodulation of envelopes on multiple electrodes might also be beneficial for detection in electric hearing. CMR was investigated with normal-hearing participants listening to unprocessed or vocoded stimuli. In Experiment 1, tone thresholds were determined when masked by a sinusoidally amplitude-modulated band of noise (SAM and OFB) and by zero to four FBs of noise whose envelopes were either co- or anti-modulated with the OFB envelope. In Experiment 2, envelopes of those signals were extracted in a vocoder and used to modulate noise or sinusoidal carriers, thereby replacing the original temporal fine structure (TFS). Significant CMR of 3-10 dB was found in unprocessed conditions and although reduced to 2-6 dB, CMR was still significant after vocoding. CMR did not differ significantly between the sine and the noise vocoder, suggesting that the applied SAM determined the magnitude of CMR. Since CMR withstands vocoding, comodulation is hoped to improve detection in electric hearing.
Authors:
Robert H Pierzycki; Bernhard U Seeber
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  The Journal of the Acoustical Society of America     Volume:  127     ISSN:  1520-8524     ISO Abbreviation:  J. Acoust. Soc. Am.     Publication Date:  2010 Mar 
Date Detail:
Created Date:  2010-03-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503051     Medline TA:  J Acoust Soc Am     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1808     Citation Subset:  IM    
Affiliation:
MRC Inst. of Hearing Res., Univ. Park, Nottingham NG7 2RD, United Kingdom, rp@ihr.mrc.ac.uk.
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