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Basilar membrane measurements and the travelling wave
Hearing Research
|January 1, 1986
Summary
The basilar membrane (BM) is now understood to be highly nonlinear and sharply tuned, explaining many auditory nerve responses. This nonlinearity, originating from outer hair cells, is crucial for normal hearing function.
Area of Science:
- Auditory Neuroscience
- Bioengineering
- Physiology
Background:
- Historically, the basilar membrane (BM) was viewed as a passive, linear vibratory system.
- Recent research has revealed the BM's complex nonlinear and sharply tuned mechanical properties.
Purpose of the Study:
- To investigate the nonlinear mechanics of the basilar membrane and its role in auditory perception.
- To elucidate the contribution of outer hair cells to BM nonlinearity and auditory function.
Main Methods:
- Analysis of basilar membrane vibration measurements.
- Characterization of nonlinear input-output functions.
- Comparison of basilar membrane and cochlear microphonic responses.
Main Results:
- The BM exhibits significant nonlinearity, approximated by a hyperbolic function, crucial for auditory nerve response properties.
- Nonlinearity is linked to outer hair cell activity, with half-saturation at 10 nm displacement.
- Induced hearing loss eliminates BM nonlinearity, while cochlear microphonics retain it, suggesting pathology in active feedback mechanisms.
Conclusions:
- The basilar membrane's mechanical behavior is actively controlled by a nonlinear mechano-electrical process involving outer hair cells.
- Hearing loss likely stems from disruptions in this active feedback mechanism rather than the receptor system itself.
- Understanding BM nonlinearity is key to explaining auditory sensitivity and frequency selectivity.