Linear and nonlinear model of the human middle ear

Area of Science:

• Biomedical Engineering
• Acoustics
• Otolaryngology

Background:

• Traditional middle ear transfer function measurements are invasive.
• Developing non-invasive models is crucial for understanding middle ear mechanics.
• Previous models often lack the ability to capture nonlinear phenomena.

Purpose of the Study:

• To develop a non-invasive analog model for evaluating middle ear transfer function.
• To predict intracochlear pressure and stapes volume velocity under varying sound pressure levels (SPL).
• To represent nonlinear middle ear mechanisms, including acoustic reflex and stapes displacement.

Main Methods:

• Development of both linear and nonlinear analog models of the middle ear.
• Validation of the linear model against human eardrum impedance and transfer function data.
• Incorporation of variable electrical components to simulate nonlinear phenomena like stapedius muscle contraction and stapes clipping.
• Modeling the acoustic reflex based on experimental observations and annular ligament behavior in cats, extrapolated to humans.

Main Results:

• The linear model showed good agreement with human middle ear data.
• The nonlinear model successfully represented phenomena occurring at high SPLs (acoustic reflex > 80 dB, stapes clipping > 120 dB).
• The model provides a method to evaluate middle ear characteristics without invasive procedures.

Conclusions:

• The developed analog model offers a non-invasive approach to assess middle ear transfer function.
• The model effectively captures key nonlinear mechanisms in the middle ear under intense acoustic conditions.
• This research enhances the understanding of middle ear nonlinearities and acoustic reflex pathways.