Emma Friedan, age 11, of Watertown, N.Y., for her question:
WHAT CAUSES DEAFNESS?
Deafness is the partial or complete inability to hear. About seven out of every 100 children in American public schools cannot hear as well as they should.
Some persons are born deaf. Others lose their hearing from disease or other causes. Injury to the auditory nerve by accident or disease will cause deafness. Meningitis may destroy the nerve and cause deafness or it may be caused by epilepsy or other diseases affecting the parts of the brain which register sound.
Most hearing troubles are caused by disease. This disease does not start within the ear but reaches the ear from other parts of the body, usually the nose and throat.
Such diseases are particularly important during childhood, when hearing may be injured permanently. The common cold, tonsillitis, scarlet fever, measles and some other diseases are often causes of such deafness.
Infection in the throat and nose may move up the Eustachian tube to the middle ear and cause inflammation and thickening of the eardrum. Often an abscess is formed in the inner ear and presses inside on the eardrum. Earache is the symptom of this pressure.
If the eardrum bursts, the pressure is relieved and the pain is gone, but the eardrum is damaged. If the drum can be pierced by a physician before it bursts, the hole will be small and sharply cut, and will heal sooner with less scar tissue than if it ruptures.
Often contaminated or infected fluids are forced up the Eustachian tube. This results in infection of the middle ear. Pressure of deep swimming and diving may force impure water into the middle ear. Severe nose blowing may result in a similar condition.
Infected adenoids may also spread infection into the middle ear sometimes.
Sometimes the delicate mechanism in the middle and inner ears become bony, so that the parts cannot vibrate. This is called otosclerosis and usually appears to be hereditary.
Ordinarily the human ear can hear sounds which have vibrations of from 20 to 20,000 cycles a second. The ordinary tones in conversation range from 200 to 3,000 vibrations per second in pitch.
Some animals seem to hear vibrations of higher pitch.
Sound is measured in decibels, a technical unit. A whisper is about 20 decibels in intensity while ordinary conversation is about 50 to 60 decibels.
Hearing is considered good if all the sounds between 64 and 8,192 vibrations at 20 decibels are heard. Deafness which handicaps the person begins when the tones in ordinary speech cannot be heard at a whisper.
Deafness can increase until it is almost imposible to hear any sound, but it has been found that most deaf persons can hear at least one sound.
It is essential that any deafness or condition tending to cause deafness should be remedied at once. Treatment should be obtained from a competent physician.