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Auditory filter asymmetry in the hearing impaired
The Journal of the Acoustical Society of America
|November 1, 1984
Summary
This study measured hearing thresholds in normal and hearing-impaired listeners using notched-noise masking. Results reveal varied auditory filter shapes in hearing loss, impacting susceptibility to masking effects.
Area of Science:
- Auditory Neuroscience
- Psychoacoustics
- Audiology
Background:
- Understanding auditory filter shapes is crucial for diagnosing hearing loss.
- Previous research established methods for auditory filter analysis using notched-noise maskers.
Purpose of the Study:
- To determine auditory filter shapes in individuals with normal hearing and cochlear hearing loss.
- To investigate the relationship between auditory filter characteristics and susceptibility to masking effects.
Main Methods:
- Thresholds for 2-kHz sinusoidal signals were measured using a notched-noise masker in 6 normal-hearing and 12 hearing-impaired listeners.
- Symmetric and asymmetric notch placements were employed, following Patterson and Nimmo Smith (1980).
- Auditory filter shapes were calculated using the rounded-exponential filter model.
Main Results:
- Six hearing-impaired listeners exhibited shallow low-frequency skirts, indicating susceptibility to upward spread of masking.
- Two hearing-impaired listeners showed shallow high-frequency skirts, suggesting susceptibility to downward spread of masking.
- Some listeners with mild losses had steeper, more symmetric filters, possibly due to conductive loss or non-degrading sensorineural factors.
Conclusions:
- Auditory filter shapes vary significantly in individuals with cochlear hearing loss.
- These variations explain differential susceptibility to upward and downward spread of masking.
- Filter characteristics can provide insights into the nature of hearing impairment, distinguishing between frequency resolution degradation and other factors.