How the Ear Works
The ear is comprised of four components: Outer ear, middle ear, inner ear and central auditory pathway. Each part serves to convert sound waves into signals that the brain interprets. The outer ear is the visible external cartilage that is called the pinna. It serves to funnel or direct the sound in from the outside world and down into the ear canal. The ear canal is a one inch long tube with an S-curve shape. The skin is lined with hairs and glands that produce ear wax and serve to protect the ear from debris and bugs from entering it and other environmental factors. The wax lubricates the skin and keeps is moist. Once the sound get to the end of the tube it vibrates against the ear drum.. This is when the sounds enters into the middle ear. The ear drum vibrates from sound waves and then proceeds to vibrate the smallest chain of bones called ossicular chain. These bones are called the Malleus (hammer), Incus (anvil), and Stapes (stirrup). The ossicles transform vibrations created by the ear drum across the chain and vibrate the round window in the cochlea (known as the organ or hearing). At this point the sound is entering the inner ear. The round window transforms the vibrations to hydraulic energy into the fluid inside the cochlea and activates the tiny hair cells called stereocilia. These hair cells then transform the energy by releasing chemical messengers to stimulate the hearing nerves to carry sound signals to the brain. The final organ of hearing and interpretation. The balance system is also part of the inner ear, but it will not be discussed in this forum. It is important to note that while many things can cause dizziness and balance problems, having the hearing system evaluated as part of the diagnosis for these symptoms is critical. The auditory pathways contain circuitry of the nerves that lead from the inner ear to the brain stem. From the brain stem these signals are transmitted to the cerebral cortex at the temporal lobe. This is the part of the brain that processes the stimuli as speech and language as well as tonal stimuli for environmental sounds such as music.
Anywhere along this pathway, from the outer ear to the brain, can experience a disruption in the sound transmission and thus create a hearing loss.