How Does the Human Ear Work?

Outer Ear

The outer ear is the the only part of the human ear that is visible. The part of the ear that protrudes from the head is called the pinna. The pinna helps to direct sound waves into the rest of the ear, but it is not essential for the ear's function. Ear wax is produced by glands in the skin on the outer ear. Ear wax helps protect the ear canal. The skin on the outer part of the ear canal rests on cartilage and the skin on the inner part lies on the bones of the ear. The very innermost part of the outer ear is the ear drum which translates sound waves into vibrations.

Middle Ear

The middle ear is a space behind the ear drum that is filled with air. Inside the middle ear are the three bones of the ear, also known as the ossicles. The three ossicles are the malleus, the incus and the stapes; these bones are also known as the hammer, the anvil and the stirrup, respectively.

Also inside the middle ear is the Eustachian tube, which helps regulate pressure within the sinuses. The malleus connects to the incus, which connects to the stapes. These ossicles all work together to help amplify the signal that the ear drum transmits. The stapes connects to a membrane called the oval window, which is the interface between the middle and inner ear.

Inner ear

The inner ear has two separate parts. The portion that is responsible for hearing is the cochlea. The other part, which is involved in balance, is called the vestibular apparatus. The cochlea is filled with fluid. When the oval window vibrates, it causes the fluid within the inner ear to move around. Inside the cochlea is a membrane that has a varying thickness. The vibrations of the oval window have a different frequency which corresponds to the different pitches of the sound that the ear is interpreting. The frequency of the oval window's vibration is transmitted to the fluid waves within the inner ear. The fluid within the inner ear crosses over the membrane in the inner ear depending on its frequency, which stimulates nerves, which then transmits a signal to the brain.