Hearing Disorders and Deafness
Hearing impairment is defined by IDEA as “an impairment in hearing, whether permanent or fluctuating, that adversely affects a child’s educational performance.” Deafness is defined as “a hearing impairment that is so severe that the child is impaired in processing linguistic information through hearing, with or without amplification.”
Hearing disorders make it hard, but not impossible, to hear. They can often be helped. Deafness can keep you from hearing sound at all. What causes hearing loss? Some possibilities are Heredity, Diseases such as ear infections and meningitis, Trauma, Certain medicines, Long-term exposure to loud noise, Aging. There are two main types of hearing loss. One happens when your inner ear or auditory nerve is damaged. This type is permanent. The other kind happens when sound waves cannot reach your inner ear. Earwax build-up, fluid or a punctured eardrum can cause it. Untreated, hearing problems can get worse. If you have trouble hearing, you can get help. Possible treatments include hearing aids, special training, certain medicines and surgery.
It is useful to know that sound is measured by its loudness or intensity (measured in units called decibels, dB) and its frequency or pitch (measured in units called hertz, Hz). Impairments in hearing can occur in either or both areas, and may exist in only one ear or in both ears. Hearing loss is generally described as slight, mild, moderate, severe, or profound, depending upon how well a person can hear the intensities or frequencies most greatly associated with speech. Generally, only children whose hearing loss is greater than 90 decibels (dB) are considered deaf for the purposes of educational placement.
There are four types of hearing loss. Conductive hearing losses are caused by diseases or obstructions in the outer or middle ear (the conduction pathways for sound to reach the inner ear). Conductive hearing losses usually affect all frequencies of hearing evenly and do not result in severe losses. A person with a conductive hearing loss usually is able to use a hearing aid well or can be helped medically or surgically.
Deafness in dogs can result from many causes (aging, drug toxicity, noise, infection, trauma), but the cause of significant concern to owners of English Setters and other similarly affected breeds is congenital sensorineural deafness, because it appears to be inherited. Although described as congenital (present at or near birth), the deafness actually is not present until age 3-4 weeks. Cochlear development occurs normally to that point, but the vascular supply to the cochlea (the stria vascularis) degenerates, so the hair cells of the cochlea die. This is known as sensorineural deafness because the sensory nerve cells, the hair cells, die.
Nonsyndromic deafness is hearing loss that is not associated with other signs and symptoms. In contrast, syndromic deafness involves hearing loss that occurs with abnormalities in other parts of the body. Different types of nonsyndromic deafness are named according to their inheritance patterns.Most forms of nonsyndromic deafness are associated with permanent hearing loss caused by damage to structures in the inner ear. The inner ear consists of three parts: a snail-shaped structure called the cochlea that helps process sound, nerves that send information from the cochlea to the brain, and structures involved with balance.
