How do we hear?
The ear has 3 parts: the outer ear, the middle ear, and the inner ear:
- The outer ear includes the part on the side of your head (the pinna), the external auditory canal, and the eardrum.
- The middle ear is an air-filled space behind the eardrum that contains 3 tiny bones (ossicles), the Eustachian tube, and the oval window.
- The inner ear includes the cochlea, the semicircular canals, and the vestibular cochlear nerve.
Sound begins as a wave caused when movement stirs air particles. The wave enters the ear canal through the pinna and causes the eardrum to vibrate. This causes a chain reaction through the bones of the middle ear to the oval window. The oval window connects to the cochlea, which contains fluid. The fluid vibration moves hair cells in the cochlea, and the movement of the hair cells stimulates the vestibular cochlear nerve. The nerve passes the impulse to the brain, which interprets it as sound.
What is hearing loss?
A hearing loss can occur when there is a problem with any part of the hearing process. Hearing loss can range from mild (having trouble hearing some sounds) to total (cannot hear at all). Children who have a profound or total hearing loss are considered deaf.
How common is hearing loss in children?
Hearing loss is the number one birth defect in the country. According to the Centers for Disease Control and Prevention, each year in the United States, more than 12,000 babies are born with a hearing loss, and approximately 1 in 1,000 newborns is born extremely deaf.
What are the types of hearing loss?
There are 3 types of hearing loss:
- Conductive: This type of hearing loss occurs when there is a problem with the sound getting through the outer or middle ear. This can be caused by:
- Wax buildup.
- Fluid in the ear.
- Damage to the eardrum or middle ear bones birth defects, or a hereditary condition (passed down from the parents).
Conductive hearing loss may not be permanent, and can often be treated with medicine or surgery.
- Sensorineural: This is a problem with the inner ear, especially the vestibular cochlear nerve. Causes of sensorineural hearing loss include:
- Abnormal development in the womb.
- Injury from certain diseases and infections.
- Certain medicines.
- Fluid backup.
- Overexposure to loud noise (which kills the hair cells).
This type of hearing loss is permanent. In many cases, sensorineural hearing loss can be treated with hearing aids.
- Mixed: This is a combination of conductive and sensorineural hearing loss.
What are the risk factors for hearing loss?
A risk factor is a condition that increases the chances of getting a disorder. Risk factors for hearing loss in children include:
- Otitis media (ear infections, the most common cause of hearing loss in young children).
- Craniofacial abnormalities (the head, face, or ears are shaped differently).
- Family history of hearing loss.
- Exposure to infection in the womb.
- Ototoxic medicines (damaging to the auditory system).
- Syndromes that are associated with hearing loss, like Down syndrome or Usher syndrome.
- Being in the neonatal intensive care unit more than 5 days.
- Certain diseases, such as syphilis, rubella, and bacterial meningitis.
- Head trauma (injury).
How do I know if my child has hearing loss?
Almost all infants will have a hearing screening before they leave the hospital. However, hearing loss can occur as a child gets older. Here are some signs to look for in your child.
Babies with hearing loss:
- Are not startled by loud noises by 3 or 4 months of age;
- Do not turn to the source of a sound after 6 months of age;
- Do not say “Mama” or “Dada” by 1 year;
- React only when he or she sees you, not when you say his or her name;
- Have trouble holding their heads steady; are slow to sit up or walk.
Older children with hearing loss:
- Do not always respond when called;
- Hear some sounds but not others;
- Have delayed or unclear speech;
- Do not follow directions;
- Often say, “Huh?” or “What?”;
- Turn up the volume on the television or radio;
- Have problems in school;
- Have attention or behavior problems;
- Have difficulty hearing in one or both ears on the phone.
How are children tested for hearing loss?
Infants who fail their newborn screening, or a child of any age who shows signs of a hearing loss, should get a full hearing test by an audiologist (a specialist in hearing). The tests include:
- Auditory brainstem response (ABR): checks the brain’s response to sound.
- Otoacoustic emissions (OAE): checks the inner ear’s response to sound.
- Behavioral audiometry evaluation: shows how an alert child responds to sound overall. Pure tone audiometry: measures hearing levels.
What can be done for a child with hearing loss?
Hearing loss can affect a child’s speech, learning, and social development, which is why it’s important to deal with it early. Treatments for children with hearing loss include:
- Hearing aids: A hearing aid is a device worn in or near the ear that make sounds louder.
- Cochlear implant: This device uses a microphone, microcomputer, and an electrode to stimulate the vestibular cochlear nerve.
- Ear tubes: Ear tubes are used to help drain fluid from the middle ear. Too much fluid can lead to hearing loss. (Ear tubes and cochlear implants are surgeries.)
- Speech and language therapy: Many communities and health care organizations have programs for children with hearing loss. These programs help the child learn to communicate.
- Education: Your child should have an Individual Education Plan (IEP) for school to address his or her needs with a hearing loss.
- Follow-up: Your child will need continuing care by his or her doctors and audiologist.
Can hearing loss in children be prevented?
To prevent hearing loss in your child:
- Eat right and see your obstetrician on a regular basis while you are pregnant.
- Make sure your child gets all the recommended vaccinations.
- Seek treatment immediately at the first sign of an ear infection.
- Limit your child’s exposure to loud noise.
What is the outlook for a child with hearing loss?
The outlook depends on how much hearing loss the child has suffered, and on the treatments used. Children with hearing loss can live full, happy lives and learn to communicate in different ways. In many cases, with early treatment, children with hearing loss can be in the same classrooms with hearing children.
When should I call my child's healthcare provider about hearing loss?
Call your child’s doctor immediately if your child’s hearing suddenly changes or he or she shows signs of hearing loss.