The “How?” of Hearing

The ear itself

Your ear consists of three sections: the outer, middle and inner ear.

The outer ear – the ear you can see – referred to as the pinna or auricle is connected by its ear canal to the middle ear. The eardrum or tympanic membrane separates the outer and middle ears.

The middle ear contains the three ossicles which are tiny connected bones: the malleus, incus & stapes (referred to as the hammer, anvil & stirrup because of their respective shapes)

The inner ear’s entrance is an oval window and the footplate of the stapes bone covers this opening. Also known as the cochlea, the inner ear is lined with cilia, microscopic hairs and filled with fluid. The inner ear is the actual hearing organ of the body.

Functions

The outer ear’s primary purpose is to collect and carry sounds in the form of waves or vibrations to the middle ear. The impact of sound waves traveling through the outer ear canal and striking the eardrum creates vibrations thereby converting the sound waves into mechanical energy.

This energy pulsates into the middle ear where the malleus, incus, and stapes move because of the rhythm of the eardrum. Movement of the smallest bone, the stapes, causes the oval window separating the middle ear from the inner ear to vibrate in turn. When the oval window vibrates, fluid in the inner ear transmits the vibrations into the inner ear.

Vibrating sound waves entering the inner ear cause ripples in the fluid, bending the cilia. The movement sets off nerve impulses that are passed through the auditory nerve to the hearing center of the brain. This center translates these impulses into what the brain recognizes as sound, which is how we hear.

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