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Understanding Hearing Loss: How We Hear

The Central Auditory System

The central auditory system is made up of neurons that form the auditory nerve and several other nerve centers in the brain. These neurons are responsible for transmitting and decoding signals into meaningful entities. Speech is a highly complex auditory signal that could not be interpreted were it not for the sophistication of the central auditory system. Where the ear is said to permit the sensation of sound, the central auditory system permits the comprehension of sound. A lack of stimulation of the central auditory system, as often seen in cases of hearing impairment, has been shown to cause irreversible loss in nerve function and has also been shown to contribute to dementia-like disorders in certain patients. As such, a timely correction of hearing loss is recommended to avoid such serious conditions.


The Ear is made up of three main parts:

  • Outer Ear
  • Middle Ear
  • Inner Ear

Outer Ear

The outer ear consists of the visible part of the ear (pinna), the ear canal and the eardrum. Sound waves are collected by the outer ear and are channeled toward the eardrum. The ear-drum begins to vibrate.

Middle Ear

The middle ear is an air-filled space that contains the three smallest bones in the human body: the malleus, the incus and the stapes. These bones are attached to the eardrum on one side and to the inner ear on the other side. The middle ear is also connected to the throat via the Eustachian tube. Eustachian tubes stabilize the air pressure on either side of your eardrum and allow your ears to “pop” when you’re flying in a plane or driving through mountains. When sound waves are channeled into the eardrum, the vibration of the eardrum causes movement of the three tiny bones in the middle ear. The movement of these bones transmits the eardrum vibrations to the inner ear.

Inner Ear

The inner ear consists of the cochlea and the vestibular (balance) system. The cochlea is a snail shaped bone filled with fluid and thousands of tiny “hair cells” that process sound vibrations. Vibrations entering the cochlea create waves in the cochlear fluid, and the hair cells move in response. The movement of these hair cells sends electrical signals along the hearing nerve to the brain. The brain then processes these signals to interpret what we have heard.