How is impedance matching achieved in the ear?

The matching of impedances is accomplished in two ways: primarily by the reduction in area between the tympanic membrane and the stapes footplate and secondarily by the mechanical advantage of the lever formed by the malleus and incus.

How does the middle ear do impedance matching?

The functions of the middle ear are: The hydraulic lever concentrates acoustic energy at the oval window and results from the 17- to 20-fold difference in vibratory surface of the tympanic membrane compared with the smaller area of the stapes footplate. This is thought to be the main impedance matching mechanism.

How do you measure ear canal resonance?

The resonance of the external ear can be quantified by measuring the level of absolute sound pressure generated in the tympanic membrane for a given input sound, known as real-ear unaided response (REUR).

What the human ear detects as sound?

The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes. Hair cells near the wide end of the snail-shaped cochlea detect higher-pitched sounds, such as an infant crying.

What is the impedance matching mechanism of the middle ear?

Impedance matching mechanism of middle ear. Impedance matching is one of the important functions of middle ear. The middle ear transfers the incoming vibration from the comparatively large, low impedance tympanic membrane to the much smaller, high impedance oval window. Middle ear is an efficient impedance transformer.

Where does the geometry of the ear canal come from?

The ear canal geometry is derived from measurements of test subjects as reported in literature. The built-in physiological impedance models for the Human eardrum and the Skin are used to account for the impedance of the ear canal boundaries.

Can a coupler be used to simulate an ear canal?

Ear canal simulators or couplers can be used to simulate the acoustics of a standard human ear canal.

How are the acoustics of the ear canal modeled?

Since the human eardrum has a nontrivial acoustic behavior, the coupler has to account for both the acoustic energy losses at the eardrum and the acoustics of the cylinder, like the volume of the ear canal. The inclusion of the side volumes and the slits is necessary to mimic the complex eardrum’s mechanical losses using an acoustic system.