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Combined effect of fluid and pressure on middle ear function
Chenkai Dai1, Mark W Wood, Rong Z Gan
1School of Aerospace and Mechanical Engineering and Bioengineering Center, University of Oklahoma, 865 Asp Avenue, Room 200, Norman, OK 73019, United States.
Hearing Research
|December 29, 2007
Summary
This study reveals how fluid and pressure together impact middle ear function, showing non-additive effects on tympanic membrane movement. Negative pressure combined with fluid significantly altered middle ear function.
Area of Science:
- Otolaryngology
- Biomedical Engineering
- Acoustics
Background:
- Previous research examined fluid effusion and pressure independently affecting middle ear sound transmission.
- Understanding the combined impact of effusion and pressure is crucial for middle ear function analysis.
Purpose of the Study:
- To investigate the synergistic effects of fluid effusion and pressure on middle ear mechanics.
- To quantify the combined influence of fluid and pressure on tympanic membrane displacement and middle ear compliance.
Main Methods:
- An in-vitro model of otitis media with effusion was created using human temporal bones.
- Simultaneous injection of saline and air pressure into the middle ear.
- Measurement of tympanic membrane displacement via laser vibrometry and middle ear compliance using tympanometry.
Main Results:
- The combination of fluid and pressure reduced tympanic membrane umbo movement by up to 17 dB across auditory frequencies.
- The effects of fluid and pressure were non-additive, differing from individual impacts.
- Negative middle ear pressure in the fluid-pressure combination demonstrated a greater effect on middle ear function than positive pressure.
Conclusions:
- The combined presence of fluid and pressure significantly alters middle ear function in a non-additive manner.
- Negative pressure combined with effusion has a more pronounced effect on middle ear mechanics.
- Tympanometry is capable of detecting the pressure component within a fluid-pressure middle ear condition.
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