How We Hear

The Outer Ear
The Outer Ear consists of the visible part of the ear, also called the auricle, and the ear canal.Sound Waves,that are transmitted by air,are collected and guided through the ear canal to the Eardrum. The eardrum is a flexible, circular membrane that vibrates when sound waves strike it.

The Middle Ear
Middle-Ear is an air-filled space separated from the outer ear by the eardrum, or the tympanic membrane. In the middle ear are three tiny bones: malleus, incus, and stapes, often referred to as the hammer, the anvil, and the stirrup. They are collectively known as the ossicles. These form a bridge from the eardrum to the inner ear. The ossicles also vibrate in response to movements of the eardrum and in doing so, amplify and relay the sound to the inner ear.

The Inner Ear
Inner Ear referred to as the cochlea, is similar in shape to a snail shell. It contains several membranous sections filled with fluids. When the ossicles conduct sound to the oval window, the fluid begins to move, thus stimulating the minute hearing nerve cells, called hair cells, inside the cochlea. These hair cells in turn send electrical impulses via the auditory nerve to the brain where it will be interpreted as sound.

How Ears work

The outer ear directs sound waves from the external environment to the tympanic membrane. The auricle, the visible portion of the outer ear, collects sound waves and, with the concha, the cavity at the entrance to the external auditory canal, helps to funnel sound into the canal. .

Sounds reaching the tympanic membrane are in part reflected and in part absorbed. Only absorbed sound sets the membrane in motion. The tendency of the ear to oppose the passage of sound is called acoustic impedance. The magnitude of the impedance depends on the mass and stiffness of the membrane and the ossicular chain and on the frictional resistance they offer..