- Conductive hearing loss
- Otitis media
- Central auditory processing disorders
- Congenital hearing loss
- Other genetically based hearing losses
- Meniere's disease
- Sudden deafness or sudden sensorineural hearing loss
- Treatment team
- Recovery and rehabilitation
- Clinical trials
- Special concerns
Hearing disorders range from a temporary, partial loss of hearing to the permanent loss of hearing known as deafness.
The variety of hearing disorders includes a loss or decrease in the ability to discern certain frequencies of sound, a ringing or other noise that is unrelated to any actual external sound, damage due to physical trauma or infection, and genetically determined structural malformation.
Hearing disorders occur worldwide in all races. The hearing loss that occurs with age is very common, affecting an estimated 30% of Americans over 60 years of age and 50% of those older than 75.
Tinnitus, a ringing or noisy sensation in the ears, is quite common with an estimated 20% of people affected worldwide. In the United States alone, some 36 million people experience tinnitus.
For hearing loss caused by otosclerosis, middle-aged Caucasian women are more prone than others, perhaps as a consequence of hormonal changes. In otosclerosis, abnormal bone development occurs in the middle ear, resulting in progressive hearing loss. Sudden hearing loss happens more often to people ages 30–60 for unknown reasons.
Presbycusis (or sensorineural hearing loss) is the loss of hearing that occurs with age. The condition results from the long-term assault on the ear structures, particularly on the inner ear, from a lifetime of noise, ear infections, or growths on bones of the outer or middle ear. The inner ear is where the vibrational sound waves are converted to electrical signals, courtesy of thousands of tiny hairs that are in a fluid-enclosed space called the cochlea. The hairs are connected to nerve cells, which send the electrical signals to the brain.
Most age-related hearing loss is due to damage to the cochlea. The tiny hairs can bend or even break, and the attached nerve cells can degenerate. The resulting less-efficient transmission of the electrical signal, particularly of higher-pitched tones, causes hearing loss.
Symptoms of presbycusis typically include increased difficulty in making out sounds of a certain volume or tone, especially when background sounds are present.
Author Info: Brian Douglas Hoyle PhD, The Gale Group Inc., Gale, Detroit, Gale Encyclopedia of Neurological Disorders, 2005