What Is It?
Hearing loss is the reduced ability to hear sounds in the range of normal human speech. More than 7 million children have hearing loss, which can be present at birth (congenital) or can develop later in life (acquired). Hearing loss is one of the most common congenital problems in newborns, affecting one to three out of every 1,000 healthy babies. It happens even more frequently in babies born with other serious medical problems. The condition can be inherited; 5 percent to 10 percent of deaf children have deaf parents.
Unfortunately, hearing loss often is not detected until a child is 2, 3 or even 4 years old. Since the critical period for language development is from birth to age 3, the failure to identify hearing loss at a young age can have serious implications for a child’s speech.
There are two major categories of hearing loss:
- Central hearing loss involves problems with the transmission of information between the ear and the brain.
- Peripheral hearing loss refers to problems with the ear structures. There are three types of peripheral hearing loss:
- Conductive hearing loss, the most common type in children, occurs when the transmission of sound through the external or middle ear is blocked. The condition can be temporary or permanent, and 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 is acquired during childhood as the result of middle-ear infections (otitis media). Other causes include perforation of the eardrum, impacted earwax or objects in the ear canal.
- Sensorineural hearing loss involves problems with the conduction of sound information from hair cells deep within the ear to the nerve that supplies information to the brain. It is a permanent condition that usually affects both ears. Sensorineural hearing loss can be present at birth, or occur later in life. Causes include prolonged exposure to loud noise, infection (for example, bacterial meningitis), 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. Typically, 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, but is often difficult to detect, especially in young children. Babies with hearing loss may not do the following, which are typical developmental milestones in children with normal hearing:
- 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”), and 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”), and 50 percent of the child’s words are understood by strangers.
- 25 to 36 months — The child uses three- to five-word sentences, and 75 percent 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
Hearing loss often is discovered when a child is being evaluated for difficulty with school performance or behavior. It is important to identify hearing loss as early as possible since even slight hearing loss in one ear can have an impact on a child’s speech and language development.
An evaluation for suspected hearing loss often starts with a medical history and physical examination. The doctor looks for deformities of the ear, problems with the eardrum (including signs of middle-ear infection), accumulation of earwax or objects in the ear.
Various tests can be performed to assess hearing loss, including the following:
- Tympanogram — This screening test for middle-ear problems measures the air pressure in the middle ear and the mobility of the eardrum. The results are printed as a graph.
- 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, so the test usually is not done on children younger than 5 or 6. For a child between 2½ and 5 years old, this test is varied so that the child responds to the sounds by playing a game. In children less than 2½ 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 is not ear-specific.
- 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, which can then be studied to give information abut 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. Children age 6 months to 4 years often need to be sedated during this test so that their movements don’t interfere with the recording.
- Otoacoustic emissions — This relatively quick, noninvasive test involves placing a miniature microphone in the ear to pick up signals that are normally emitted from the hair cells in the inner ear. Like the auditory brain stem response test, it does not test hearing directly, but it does provide an excellent screening test in newborns and infants. If a hearing deficit is noted, 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. This includes:
- 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, whether or not they have any risk factors for this problem.
Some conditions that cause hearing loss are permanent. Others, such as fluid behind the eardrum associated with an infection, are temporary, although it may take several months for the problem to go away.
Many of the 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 (especially pop music), firecrackers, toy cap guns, firearms, squeaking toys (some are loud enough to cause damage with only a few minutes of exposure per day), lawn mowers and leaf blowers, snowmobiles and other recreational vehicles, and 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 behind the eardrum can be treated and the child’s hearing can be monitored. Surgery may be considered for some abnormalities.
Sensorineural hearing loss is treated with hearing aids that amplify sound. They can be fitted for children as young as 2 months 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 cochlear implant. This device is surgically implanted in the skull. It functions like the hair cells in the inner ear, helping to translate sound waves into signals that can reach the brain. Cochlear implants are approved in the United States for use in adults and children older than 2 years of age. Children with significant hearing loss also can learn sign language (along with their family members) and lip reading to communicate with others.
Controversies exist regarding different treatment methods. Therefore, each option should be carefully assessed with respect to the needs of the child and his or her family.
When To Call A Professional
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 prognosis is better if the problem is detected and treated early.
Diseases and Conditions Center
All ArmMed Media material is provided for information only and is neither advice nor a substitute for proper medical care. Consult a qualified healthcare professional who understands your particular history for individual concerns.