In the first few years of life, hearing is a critical part of a child’s social, emotional, and cognitive development. Even a mild or partial hearing loss can affect a child's ability to speak and understand language.
Hearing loss is a very common birth defect. Approximately 1 to 3 out of every 1,000 babies is born with some degree of hearing loss. There are a number of factors that can lead to hearing loss, and about half the time, no cause is found.
The good news is, hearing problems can be treated, if they’re caught early – ideally by the time a baby is three-months old. So it's important to get your child’s hearing screened early, and evaluated on a regular basis throughout life.
Causes of Hearing Loss
- was born prematurely
- stayed in the neonatal intensive care unit
- had high bilirubin requiring a transfusion
- was given medications that can lead to hearing loss
- has a family history of childhood hearing loss
- had complications at birth
- had frequent ear infections; had infections such as meningitis or cytomegalovirus
- exposed to very loud sounds or noises even of brief duration
When Should My Child's Hearing Be Evaluated?
Most children who are born with a hearing loss can be diagnosed through a hearing screening. But in some cases, the hearing loss is caused by things like infections, trauma, and damaging noise levels, and the problem doesn’t emerge until later in childhood. So it’s important to have your child’s hearing evaluated on a regular basis as he or she grows.
Your newborn will likely have a hearing screening before being discharged from the hospital. (Most states require this.) If your baby doesn’t have this screening, or was born at home or at a birthing center, it’s important to have a hearing screening within the first three weeks of life.
If your baby does not pass the hearing screening, it doesn’t necessarily mean that he or she has a hearing loss. Because debris or fluid in the ear can interfere with the test, not infrequently that these tests have to be redone in order to confirm a diagnosis.
If your newborn doesn’t pass the initial hearing screening, it’s important to get a retest within three months, in order to start treatment right away. Treatment for hearing loss can be the most effective if it’s started by the time a child is six-months old.
Kids who seem to have normal hearing, should continued to have their hearing evaluated on a regular basis at doctors’ appointments throughout life. Hearing tests are usually done at ages 4, 5, 6, 8, 10, 12, 15, and 18, and at any other time if there’s a concern. But if you are concerned that your child seems to be having trouble hearing, or if their speech development seems abnormal or their speech is difficult to understand talk with your child’s doctor.
Symptoms of a Hearing Loss
Even if your newborn passes the hearing screening, it’s important to continue to watch for signs that he or she is hearing well.
Here are some hearing milestones your child should reach in the first year of life:
- Most newborn infants startle or "jump" to sudden loud noises.
- By 3 months, a baby usually recognizes a parent's voice.
- By 6 months, an infant can usually turn his or her eyes or head toward a sound.
- By 12 months, a child can usually imitate some sounds and produce a few words, such as "Mama" or "bye-bye."
As your baby grows into a toddler, signs of a hearing loss may include:
- limited, poor, or no speech
- frequently inattentive
- difficulty learning
- often increases the volume on the TV
- fails to respond to conversation-level speech, or answering inappropriately to speech.
Types of Hearing Loss
Conductive hearing loss is caused by an interference in the transmission of sound to the inner ear. Infants and young children frequently develop conductive hearing loss due to ear infections. This loss is usually mild, temporary, and treatable with medicine or surgery.
Sensorineural hearing loss involves malformation, dysfunction, or damage to the inner ear (cochlea) or nerve of hearing and is rarely due to problems with the auditory cortex of the brain. The most common type is cochlear hearing loss and this may involve a specific part of the cochlea (inner hair cells or outer hair cells or both). It usually exists at birth. It may be hereditary or may be caused by a number of medical problems, but sometimes the cause is unknown. This type of hearing loss is usually permanent.
The degree of sensorineural hearing loss can be mild, moderate, severe, or profound. Sometimes the loss is progressive (hearing gradually becomes poorer) and sometimes unilateral (one ear only).
Because the hearing loss may be progressive, repeat audiologic testing should be done. Sensorineural hearing loss is generally not reversible medically or surgically, but children with this type of hearing loss often can be helped with hearing aids.
A mixed hearing loss occurs when both conductive and sensorineural hearing loss are present at the same time.
A central hearing loss involves the hearing areas of the brain, which may show as difficulty "processing" speech and other auditory information. This is often referred to as “Auditory Processing Disorder” and may be misdiagnosed as a behavioral disorder.
How Is My Child's Hearing Tested?
There are several methods of testing a child's hearing. The method chosen depends in part on the child's age, development, or health status.
Behavioral tests involve careful observation of a child's behavioral response to sounds like calibrated speech and pure tones. Pure tones are the distinct pitches (frequencies) of sounds. Sometimes other calibrated signals are used to obtain frequency information.
The behavioral response might be an infant's eye movements, a head-turn by a toddler, placement of a game piece by a preschooler, or a hand-raise by a gradeschooler. Speech responses may involve picture identification of a word or repeating words at soft or comfortable levels. Very young children are capable of a number of behavioral tests.
Physiologic tests are not hearing tests but are measures that can partially estimate hearing function. They are used for children who can't be tested behaviorally due to young age, developmental delay, or other medical conditions and in some conditions can help to define the function of the auditory system that is at fault.
Auditory brainstem response (ABR) test
An infant is sleeping or sedated for the ABR. An infant may be sleeping naturally or may have to be sedated for this test. Additionally, older, cooperative children may be tested in a silent environment while they are visually occupied. Tiny earphones are placed in the baby's ear canals. Usually, click-type sounds are introduced through the earphones, and electrodes measure the hearing nerve's response to the sounds. A computer averages these responses and displays waveforms. Because there are characteristic waveforms for normal hearing in portions of the speech range, a normal ABR can predict fairly well that a baby's hearing is normal in that part of the range. An abnormal ABR may be due to hearing loss, but it may also be due to some medical problems or measurement difficulties.
Auditory Steady State Response (ASSR) test
An infant is typically sleeping or sedated for the ASSR. This is a new test that currently must be done in conjunction with the ABR to assess hearing. Sound is transmitted through the ear canals, and a computer picks up the brains response to the sound and automatically establishes the hearing level. This test is still under development.
Otoacoustic emissions (OAE) test
This test is performed with a sleeping infant or an older child who may be able to sit quietly. In this brief test, a tiny probe is placed in the ear canal. Numerous pulse-type sounds are introduced, and an "echo" response from the outer hair cells in the inner ear is recorded. These recordings are averaged by a computer. A normal recordings is associated with normal outer hair cell function and this typically reflects normal hearing although in some cases the hearing loss may be due to problems in other parts of the hearing pathway.
ABR or OAE tests are often used at hospitals to screen newborns. If a baby fails a screening, the test is usually repeated. If the screening is failed again, the baby is referred for full hearing evaluation.
Tympanometry
Tympanometry is not a hearing test but a procedure that can show how well the eardrum moves when a soft sound and air pressure are introduced in the ear canal. It's helpful in identifying middle ear problems, such as fluid collecting behind the eardrum.
A tympanogram is a graphic representation of tympanometry. A "flat" line on a tympanogram may indicate that the eardrum is not mobile, while a "peaked" pattern often indicates normal function. A visual ear examination should be performed with tympanometry.
Who Should Test My Child's Hearing?
A pediatric audiologist specializes in evaluating and assisting children with hearing loss. This person works closely with physicians, educators, and speech/language pathologists.
Audiologists have a lot of specialized training. They have master's or doctorate degrees in audiology, have performed internships, and are certified by the American-Speech-Language-Hearing Association (CCC-A) or are Fellows of the American Academy of Audiology (F-AAA).
Treatment for Hearing Loss
Hearing aids are the primary non-medical treatment for hearing loss. The most common type of hearing loss involves outer hair cell dysfunction and hearing aids allow an amplification of sound to overcome this problem. A hearing aid's basic components are the microphone, amplifier, and receiver. A number of circuit options modify how the hearing aid makes certain sounds louder.
There are several hearing aid styles; some are worn on the body while others fit behind the ear or in the ear. Some specialized hearing aids are attached to the bone of the skull to send sound waves directly to the cochlea and may be used in conditions of conductive hearing loss not amenable to standard hearing aids. There is no single style or manufacturer that is best. Hearing aid selection is based on the child's individual needs. If a child has bilateral hearing loss (both ears), two hearing aids are usually worn.
Most kids with hearing loss who are benefiting from the aids tend to wear them because it "connects" them to the environment around them.
There are no exact rules for use of hearing aids - it depends on a child's individual situation. Methods of assessing how a child will benefit from a hearing aid vary with her or his age, type of hearing loss, and individual situation.
Hearing aids are expensive, due to their sophisticated technology; a hearing aid costs at least several hundred dollars. Unfortunately, hearing aids are often not covered by health insurance companies. If there are financial concerns, a family may qualify for assistance through a government program.
A specialized amplification device called an FM system may be recommended for use in school. FM systems are sometimes called "auditory trainers." They may be provided in the classroom in order to improve hearing in group or noisy environments and also have been fitted for personal or home use. There are other assistive listening or alerting devices that may help older children.
In addition to hearing aids or FM systems, hearing rehabilitation may include auditory or listening therapy and speech (lip) reading.
A cochlear implant does not restore hearing but rather transmits sound information past the damaged cochlea directly to the nerve of hearing. It is intended for children with profound hearing loss who do not benefit from hearing aids.
Updated and reviewed by: Robert C. O'Reilly, MD and Thierry Morlet, PhD
Date reviewed: June 2006
