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.
Hearing loss can show up at any age. It is often difficult to detect, especially in young children.
Following are typical developmental milestones in children with normal hearing. Babies and young children with hearing loss may not achieve these milestones:
- 0 to 3 months -- The child blinks, startles, moves with loud noises and quiets down at the sound of the parent's voice.
- 4 to 6 months -- The child turns his or her head to the side toward voices or other noises, and makes musical sounds ("ooh," "ah"). The child appears to listen and then responds as if having a conversation.
- 7 to 12 months -- The child turns his or her head in any direction toward sounds, babbles ("ba," "ga," "bababa," "lalala," etc.), and says "mama," "dada" (though not specific to mom or dad).
- 13 to 15 months -- The child points; uses "mama," "dada" correctly, and follows one-step commands.
- 16 to 18 months -- The child uses single words.
- 19 to 24 months -- The child points to body parts when asked, puts two words together ("want cookie," "no bed"). Half of the child's words are understood by strangers.
- 25 to 36 months -- The child uses three- to five-word sentences. Three-quarters of the child's words are understood by strangers.
- 37 to 48 months -- Almost all of the child's speech is understood by strangers.
Indications of hearing loss in older children can include:
- Listening to the television or radio at a higher volume than other children
- Sitting especially close to the television when the volume is adequate for others in the room
- Asking to have things repeated
- Having difficulty with school work
- Having speech and language problems
- Exhibiting poor behavior
- Being inattentive
- Complaining of difficulty hearing or blocked ears
It is important to identify hearing loss as early as possible. Ideally this means no later than 6 months of age. Hearing loss often is discovered when a child is being evaluated for difficulty with school performance or behavior. Even slight hearing loss in one ear can impact a child's speech and language development.
The doctor will ask about your child's medical history. The doctor will do a physical examination and look closely at your child's ears. The doctor looks for:
- Deformities of the ear
- Problems with the eardrum (including signs of middle-ear infection)
- Accumulation of earwax
- Objects in the ear
Various tests can be done to measure hearing loss, including:
- Tympanogram. This is a screening test for middle ear problems. It measures the air pressure in the middle ear and the ability of the eardrum to move.
- Audiometry. This test is used to determine the volume of sound the child can hear. The child listens to sounds of various volume and frequency through earphones in a soundproof room. Children are asked to respond to the sounds by raising a hand. For younger children, the child responds to the sounds by playing a game. In children less than 2 and a half years old, audiometry is also used as a rough screening test to rule out significant hearing loss. An observer watches the infant's or toddler's body movements in response to sounds. This test cannot determine which ear has a problem or whether both do.
- Auditory brain stem response (also called brainstem auditory evoked potential). In this test, sensors are stuck to the scalp to record electrical signals from nerves involved in hearing. The signals are studied to give information about hearing and hearing-related brain function. This test is used to screen newborns or to test children unable to cooperate with other methods. It also can be used to confirm hearing loss or to give ear-specific information after other screening tests have been done. Young children often need to be sedated during this test so that their movements don't interfere with the recording.
- Otoacoustic emissions. This is a relatively quick, noninvasive test. A miniature microphone is placed in the ear. It picks up signals that normally are emitted from the hair cells in the inner ear. This is an excellent screening test for all newborns. If a hearing problem is found, it should be confirmed with the auditory brain stem response test.
Testing is done routinely for infants and children at high risk of hearing loss. These include children who have:
- Developmental delays, especially in speech
- Syndromes involving the head that are associated with hearing loss
- Other risk factors, such as a history of premature birth or bacterial meningitis or a family history of hearing loss
Many hospitals now automatically screen all newborns for hearing loss. Your newborn baby should have a hearing screen done in the nursery before discharge. Ask for the results. If your baby does not pass the screening test, a specialist should evaluate your child's hearing as an outpatient.
Some conditions that cause hearing loss are permanent. Others are temporary. Still, it may take several months for the problem to go away.
Many causes of hearing loss can be prevented if you and your child take the following steps:
- Get good prenatal care.
- Get proper treatment and follow-up care for middle-ear infections.
- Avoid or minimize exposure to loud noises. Irreversible damage can result from prolonged exposure to sounds not much louder than normal speech. Such sounds can come from:
- Hair dryers
- Loud music
- Toy cap guns
- Squeaking toys
- Lawn mowers and leaf blowers
- Snowmobiles and other recreational vehicles
- Farm equipment
- Wear protective devices such as earmuffs, form-fitting foam earplugs or pre-molded earplugs when unable to avoid exposure to loud noises.
In most cases, a child needs a full developmental, speech and language evaluation before treatment is planned.
Conductive hearing loss often can be corrected. For example, middle-ear infections and the associated fluid buildup can be treated and the child's hearing can be monitored. Surgery may be considered for some problems.
Sensorineural hearing loss is treated with hearing aids that amplify sound. They can be fitted for children as young as 4 weeks of age. Treating a child before 6 months of age can make a huge difference in language and speech development.
A relatively new treatment option for severe or profound sensorineural hearing loss is a cochlear implant. This device is surgically implanted in the skull. It helps to translate sound waves into signals that can reach the brain. Cochlear implants are approved in the United States for use in children older than 1 to 2 years of age.
Children with significant hearing loss also can learn sign language and lip reading to communicate with others.
Each option should be carefully considered and discussed with your child's physician. The discussion should take into account the needs of the child and his or her family.
You should call a doctor if you have any concerns that an infant or child cannot hear normally. This may include not achieving language milestones.
The outlook is better if the problem is detected and treated early.
National Institute on Deafness and Other Communication Disorders
National Institutes of Health
31 Center Drive, MSC 2320
Bethesda, MD 20892-2320