The Human Ear & How We Hear

Overview

Anatomically speaking, the ear consists of three sections: the outer ear, the middle ear and the inner ear. The outer ear and the middle ear are used only for hearing, while the inner ear is involved in both hearing and maintaining equilibrium. Without the equilibrium capabilities of the inner ear, standing and walking would be difficult.

The Outer Ear

The outer ear consists of folds of skin and cartilage as well as the ear canal. The folds of skin and cartilage are called the pinna. The pinna’s cuplike shape helps it gather sound and direct the sound toward the ear canal. Sound travels through the ear canal to the eardrum, causing the eardrum to vibrate. The outer ear is involved only with sound transmission.

The Middle Ear

The middle ear is between the eardrum and the inner ear. This section of the ear is connected to the back of the nose and the upper portion of the throat by a tube called the eustachian tube. The eustachian tube stays closed until you yawn or swallow, then it equalizes air pressure in the middle ear, helping the eardrum vibrate normally. Like the outer ear, the middle ear is involved solely with the transmission of sound. The cavity of the inner ear contains small bones called the hammer, anvil and stirrup. These tiny bones lead to the opening of the inner ear.

The Inner Ear

The inner ear consists of bony chambers that contain the cochlea and the vestibular labyrinth. Sound vibrations travel into the fluid-filled cochlea and are converted into electrical impulses. These electrical impulses are ultimately transmitted into impulses in the brain by the auditory nerve. Inside the inner ear’s vestibular labyrinth are three semicircular tubes that contain fluid and track your body’s movement through cells that are sensitive to the fluid’s movement. This helps create your sense of balance.

Distinguishing Sounds

The brain is able to distinguish sounds through translation of the electric impulses that travel through the auditory nerve to the brain’s information processing centers. Sounds are deciphered in the auditory complex in the temporal lobe. This is where the brain files and interprets the information needed to understand sounds in the future.

Hearing Problems

Any degree of difficulty in hearing is considered deafness. Deafness falls into two broad categories: conduction and sensorineural. Conduction deafness occurs when something interferes with the conduction of sound vibrations to the fluids of the inner ear. Earwax or a ruptured eardrum are among the causes of conduction deafness. Sensorineural deafness, on the other hand, results from degeneration of or damage to the receptor cells. Excessive exposure to loud noise is one cause of sensorineural deafness.

About this Author

Cynthia Hunter is a health and fitness writer in San Diego, Calif. She is a National Academy of Sports Medicine, certified personal trainer and performance enhancement specialist. Hunter trains clientele at The Sporting Club and her expertise in health and fitness has been featured in many articles for various online publications. Hunter began writing professionally in 2009.