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Trends Hear. 2016 Jan-Dec;20:2331216516676255. doi: 10.1177/2331216516676255.

Developmental Conductive Hearing Loss Reduces Modulation Masking Release.

Author information

1
1 Department of Biomedical Engineering, New Jersey Institute of Technology, Newark, NJ, USA.
2
2 Center for Neural Science, New York University, NY, USA.
3
3 Department of Psychology, New York University, NY, USA.
4
4 Department of Biology, New York University, NY, USA.

Abstract

Hearing-impaired individuals experience difficulties in detecting or understanding speech, especially in background sounds within the same frequency range. However, normally hearing (NH) human listeners experience less difficulty detecting a target tone in background noise when the envelope of that noise is temporally gated (modulated) than when that envelope is flat across time (unmodulated). This perceptual benefit is called modulation masking release (MMR). When flanking masker energy is added well outside the frequency band of the target, and comodulated with the original modulated masker, detection thresholds improve further (MMR+). In contrast, if the flanking masker is antimodulated with the original masker, thresholds worsen (MMR-). These interactions across disparate frequency ranges are thought to require central nervous system (CNS) processing. Therefore, we explored the effect of developmental conductive hearing loss (CHL) in gerbils on MMR characteristics, as a test for putative CNS mechanisms. The detection thresholds of NH gerbils were lower in modulated noise, when compared with unmodulated noise. The addition of a comodulated flanker further improved performance, whereas an antimodulated flanker worsened performance. However, for CHL-reared gerbils, all three forms of masking release were reduced when compared with NH animals. These results suggest that developmental CHL impairs both within- and across-frequency processing and provide behavioral evidence that CNS mechanisms are affected by a peripheral hearing impairment.

KEYWORDS:

comodulation masking release; conductive hearing loss; deafness; gerbils; perceptual masking; sensory deprivation

PMID:
28215119
PMCID:
PMC5318943
DOI:
10.1177/2331216516676255
[Indexed for MEDLINE]
Free PMC Article

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