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Spectro-temporal analysis in normal-hearing and cochlear-impaired listeners.
J W Hall1, A C Davis, M P Haggard
1University of North Carolina, Division of Otolaryngology, Chapel Hill 27514.
The Journal of the Acoustical Society of America
|October 1, 1988
Summary
Hearing-impaired individuals show reduced comodulation masking release (CMR) with wider noise bandwidths. This finding suggests that poor frequency selectivity in hearing loss diminishes the effectiveness of CMR.
Area of Science:
- Auditory Neuroscience
- Psychoacoustics
- Audiology
Background:
- Comodulation masking release (CMR) is a phenomenon where detection thresholds improve when noise is modulated.
- CMR relies on across-frequency differences, which may be affected by hearing loss.
Purpose of the Study:
- To investigate the impact of hearing loss on CMR.
- To determine the relationship between frequency selectivity and CMR in hearing-impaired listeners.
Main Methods:
- Detection thresholds for a 1.0-kHz pure tone were measured in unmodulated and 15-Hz square-wave modulated noise.
- Noise bandwidths ranged from 100 to 1000 Hz.
- Frequency selectivity was assessed using notched-noise masking.
Main Results:
- Hearing-impaired subjects exhibited reduced CMR at a 1000-Hz noise bandwidth compared to normal-hearing subjects.
- Reduced CMR in hearing-impaired listeners correlated significantly with poorer frequency selectivity.
- Good frequency selectivity was found to be necessary but not sufficient for substantial CMR.
Conclusions:
- Poor frequency selectivity, common in cochlear hearing loss, impairs the ability to utilize CMR.
- The findings support the hypothesis that reduced across-frequency processing contributes to diminished CMR in hearing impairment.