The auditory system is made up of a unique set of anatomy, which allows us to detect waves of sound energy. Not only does the auditory system give us the ability to detect the smallest sounds such as a bird chirping but also more complex sounds such as an orchestra playing. This system is very complex and some mechanisms are not entirely understood. Below is a description of how the auditory system converts sounds into neural impulses the brain can recognize so we can enjoy the sounds of everyday life.

Hearing begins at the outer ear (auricle), which collects sound waves and funnels them down into the auditory canal to move the eardrum. The eardrum vibrates from the incoming sound and this vibration is conducted across the middle ear by moving a chain of the three small bones, the malleus, incus, and stapes. These small bones are the smallest in the body and are called the ossicles. The ossicles move in a coordinated motion to conduct and even amplify the softest of sounds so that they can be registered in the inner ear.

The inner ear consists of the organs of balance (vestibular system) and the organ of hearing or the cochlea. The cochlea is a spiral-shaped structure that is filled with fluid and contains thousands of microscopic hair cells.

As the eardrum vibrates and causes the ossicles to move, waves of pressure are created in the fluid inside the cochlea. These varying amounts of pressure stimulate the sensory hair cells to fire millions of electrical impulses that are recognized by the neurons leading from the cochlea to the brain. These nerve cells lead to the eighth nerve, or auditory-vestibular nerve, that sends auditory nerve fibers to different auditory areas within the brain. Passing through the brainstem, many of the nerve fibers take a neural pathway across to the other side of the brain while others continue traveling up the same side. These intricate pathways lead to the primary auditory cortex where sounds are recognized and impulses are sent on to other areas within the cortex to create a response. Language centers interpret speech and formulate language or verbal responses.

Hearing is a sophisticated event that depends upon the proper function of literally millions of structures and processes every second. Fortunately for a majority of people, all of these structures operate properly and allow us to enjoy the full beauty of the world around us. However, occasionally one or more structures within the auditory system fail and result in hearing loss, understanding problems, or even deafness.