Abby-causes Of Hearing Loss

Causes Of Hearing Loss By Abby Al-Shamsi

How Do We Hear? • Better understanding of hearing and hearing loss begins by

understanding how we hear. • Sound waves are collected by the outer ear and channeled along the ear canal to the eardrum. When sound hits the eardrum, the impact creates vibrations that cause three bones in the middle ear to move. The smallest of these bones, the stapes, fits into the oval window between the middle and inner ear. When the oval window vibrates, fluid in the inner ear transmits the vibrations into the hearing organ, called the cochlea. • In the inner ear, thousands of microscopic hair cells are bent by the wavelike action of fluid inside the cochlea. The bending of these hairs sets off nerve impulses that are then passed through the auditory nerve to the hearing center of the brain. This center translates the impulses into sounds the brain can recognize.

Diagram of the ear • • • •

Outer Ear Inner Ear Ear Drum Middle Ear – Stapes, Malleus, and Incus • Ear canal • Cochlea

Sensory Hearing Loss •This type of hearing loss is

usually not medically or surgically treatable. Most people with a sensory hearing loss find that hearing aids are beneficial.

Causes of Sensory Hearing Loss • Sensory hearing loss: occurs

when the inner ear is damaged. The most common causes are aging, inner-ear infection and noise exposure.

Neural Hearing Loss • Aging can cause degeneration of

the hearing nerves. Hearing aids may help. Another cause is a tumor that presses on the hearing nerve.

Causes of Neural Hearing Loss • Neural hearing loss: occurs when

there is damage to the hearing nerve or the nervous system. The inner ear generates neural impulses that travel through the hearing nerve to the brain.

Conductive Hearing Loss • Occurs when the outer or middle

ear fails to work properly. Sounds become "blocked" and are not carried to the inner ear. Conductive hearing losses are often treatable with medicine or surgery.

Causes of Conductive Hearing Loss • Conductive Hearing Loss: Common causes are fluid behind the eardrum or wax buildup in the ear canal. Conductive hearing loss also can occur when the eardrum or bones of the middle ear are disrupted. Normally, when fluid builds up, it drains through the eustachian tube, which opens to the throat. The eustachian tube is normally opened by swallowing, yawning and chewing. An inflammation of the tube may keep it closed, causing fluid to build up in the middle ear. This is often the result of an upper respiratory infection and can usually can be corrected.

Audiogram • -10dB to 25dB = Normal range (Grey) • • • • •

26dB to 40 dB = Mild hearing loss (purple) 41 dB to 55 dB = Moderate hearing loss (red) 56 dB to 70 dB = Moderately Severe hearing loss (green) 71 dB to 90 dB = Severe hearing loss (yellow) over 90 dB = Profound hearing loss. (blue)