Cat eardrum mechanics

The function of the eardrum and middle ear is to resolve the acoustic impedance mismatch between the air of the outside world and the fluid of the inner ear. Without an impedance matching device, very little acoustic energy would be absorbed by the inner ear and hearing would be severely limited. Although the role of the middle ear is clear, it remains a mystery how the eardrum accomplishes this task over the audible frequency range.; In the present work, a computer simulation of the cat eardrum was constructed. For the first time, the vibrations of the eardrum were fully coupled to the acoustics of the ear canal and the dynamics of the middle ear bones. The eardrum's fibrous microstructure was taken into account. This model appears to be valid up to 20 kHz. This represents a significant improvement over previous modelling efforts. With this model, the following questions surrounding the evolution and design of the eardrum have been addressed: (1) Why does the eardrum have its distinctive conical and toroidal shape? (2) What is the significance of its highly organized fibrous microstructure? (3) What is the advantage of its angular placement in the ear canal? (4) What is the benefit of having complex vibrational modes on the eardrum?; All of these features enhance the ability of the eardrum to transfer sound to the sensory epithelium inside the inner ear.