A child with hearing loss has trouble hearing sounds in the range of normal speech. Hearing loss can be present at birth or can develop later in life. Babies born with other serious medical problems are at higher risk for hearing loss. Most deaf children are born to hearing parents. But the condition can be inherited.
Hearing loss often is not detected until a child is 2, 3 or even 4 years old. The critical period for language development is from birth to age 3. The failure to identify and treat hearing loss by 6 months of age can have serious implications for a child's speech.
There are two major categories of hearing loss:
Central hearing loss involves problems with processing information in the brain.
Peripheral hearing loss refers to problems with the ear structures. There are three types of peripheral hearing loss:
Conductive hearing loss is the most common type in children. It occurs when the transmission of sound through the external or middle ear is blocked. The condition can be temporary or permanent. It can occur in one or both ears. Sometimes this type of hearing loss is caused by physical abnormalities that are present from birth. More commonly, it begins during childhood as the result of middle ear infections. Other causes include perforation of the eardrum, impacted earwax or objects in the ear canal.
Sensorineural hearing loss involves problems with the transmission of sound information from hair cells deep within the ear to the nerve that sends sound information to the brain. It is a permanent condition that usually affects both ears. Sensorineural hearing loss can be present at birth. Or it can occur later in life. Causes include prolonged exposure to loud noise, infection, severe head injury, toxic medications and some rare inherited diseases.
Mixed hearing loss is both conductive and sensorineural.
Hearing loss is measured by the volume of sounds that can be heard without amplification. It is classified as borderline or slight, mild, moderate, severe or profound.
The term "deaf" generally applies to a person whose hearing loss is so extensive that he or she cannot communicate with another person using only voice.