Measuring the Acoustic Reflex through the Tympanic Membrane.

Area of Science:

• Otoacoustic Emissions
• Middle Ear Mechanics
• Biomedical Optics

Background:

• The acoustic reflex is the middle ear's active response to loud sounds, modifying acoustic energy transfer to the inner ear.
• Understanding this reflex is crucial for diagnosing hearing loss and middle ear pathologies.

Purpose of the Study:

• To observe the effect of the acoustic reflex on tympanic membrane oscillations.
• To identify a significant nonlinear increase in membrane oscillations during the acoustic reflex.

Main Methods:

• Interferometric spectrally encoded endoscopy was used to record tympanic membrane oscillations.
• A loud, 200-ms acoustic stimulus was applied to elicit the acoustic reflex.

Main Results:

• A gradual acoustic reflex activation was measured between 40 and 100 ms.
• A 42% linear increase in umbo oscillation amplitude was observed during reflex activation.

Conclusions:

• Observed tympanic membrane oscillations align with a damped harmonic oscillator model.
• Interferometric spectrally encoded endoscopy shows potential for studying dynamic middle ear processes.