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Middle ear development. I: Extra-stapedius response in the neonatal chick
Y E Cohen1, D M Rubin, J C Saunders
1Department of Bioengineering, University of Pennsylvania, Philadelphia 19104.
Hearing Research
|February 1, 1992
Summary
The study reveals that chick middle ear sensitivity to low-frequency sounds improves with age, but high-frequency sensitivity does not. This developmental change in the extra-stapedius (ES) is linked to middle ear admittance.
Area of Science:
- Auditory Neuroscience
- Bioacoustics
- Developmental Biology
Background:
- The development of hearing involves complex changes in the auditory system's mechanical properties.
- Understanding the ontogeny of middle ear function is crucial for comprehending auditory development.
Purpose of the Study:
- To investigate the developmental changes in the mechanical responses of the chick tympanic membrane to sound.
- To measure the ontogeny of the extra-stapedius (ES) velocity and phase responses across a wide frequency range.
Main Methods:
- Utilized a laser interferometry system to measure sound-evoked responses at the tip of the extra-stapedius (ES).
- Studied auditory responses in chicks from 3 days of age to adulthood.
- Analyzed frequency-dependent sensitivity and phase responses between 0.2 and 10.0 kHz.
Main Results:
- Low-frequency ES sensitivity increased by 11 dB with age, indicating enhanced middle ear admittance.
- The slope of the low-frequency response remained constant across development.
- No consistent developmental improvement was observed in high-frequency ES sensitivity.
Conclusions:
- Chick middle ear function shows significant low-frequency developmental improvements, primarily related to increased admittance.
- High-frequency auditory development in chicks may follow different mechanisms.
- No clear correlation was found between low-frequency ES velocity, middle ear admittance, and auditory evoked potential sensitivity development.