Analysis of the Human Middle Ear Dynamics Through Multibody Modeling

Area of Science:

• Biomechanics
• Computational Auditory Science
• Medical Device Engineering

Background:

• Human middle ear (ME) dynamics are crucial for understanding hearing and the effects of conditions like conductive disease.
• Computational models, including finite element (FE) and lumped parameter (LP) models, have been used to study ME mechanics.
• Multibody (MB) models offer a balance between detailed description and computational efficiency compared to FE and LP models.

Purpose of the Study:

• To reduce a reference human middle ear (ME) finite element (FE) model to a multibody (MB) model.
• To compare the results of different levels of ME model simplification.
• To analyze the impact of ossicle flexibility, tendon/ligament stiffness, stapes footplate movement, and joint constraints on ME dynamics.

Main Methods:

• Development of a reference FE model of the human middle ear.
• Reduction of the FE model to a MB model with varying degrees of simplification.
• Comparison of model outputs using frequency response functions (FRFs) of stapes velocity to tympanic membrane sound pressure.
• Analysis of natural frequencies and mode shapes for each model.

Main Results:

• Ossicle flexibility has a minor impact on the system's frequency response function (FRF) and vibrational modes.
• Tendon and ligament stiffness significantly influence ME dynamics only when exceeding certain thresholds.
• Restricting stapes footplate motion to piston-like behavior notably affects vibrational modes.
• Constraints at the incudomalleolar joint (IMJ) and incudostapedial joint (ISJ) strongly impact the system's FRF.

Conclusions:

• Multibody (MB) models provide a viable simplification of human middle ear (ME) finite element (FE) models for analyzing dynamic behavior.
• Specific simplifications, such as joint constraints and stapes footplate movement restrictions, can significantly alter ME vibrational characteristics and overall function.
• Understanding these impacts is crucial for accurate modeling in applications like corrective surgery and middle ear prosthesis design.