Hearing ability is important for children to develop speech and language skills as they grow. In the past, hearing loss in children often went undetected until the child was around two years old, when it became obvious that he or she wasn't talking yet. Research has demonstrated that detection and intervention for hearing loss prior to six months of age results in significantly better outcomes than intervention after six months of age. As a result, newborn hearing screening has become universal in hospitals across the United States and children with hearing loss are being identified and treated at much younger ages.
Incidence and prevalance of hearing loss in children
While hearing loss is not terribly common in children, it's also not uncommon. The data points vary, but 2009 data from the CDC's Hearing Screening and follow-up survey of babies found that an average of 1.4 babies per 1,000 has hearing loss. Older data - from the CDC's National Health Interview Survey that ran from 1997 to 2005 - found that of children between the ages of 3 and 17 years old, five out of every 1,000 is affected by hearing loss.
Other data reveals more nuanced information. One 1998 report found that nearly 400,000 school-aged children had unilateral hearing loss - that is, hearing loss affecting just one ear. A 2001 article in the Journal of the American Academy of Audiology found that of the more than 700,000 individuals in the U.S. with hearing loss that could be defined as severe to profound, 8 percent of them were children.
Causes of hearing loss during childhood
There are several possible causes for hearing loss in children, whether it's congenital or acquired. Hearing losses in children can also be conductive, sensorineural or mixed. It's important that parents, caretakers, physicians, teachers and others know the signs of and address hearing loss in children because early hearing loss - especially that which is undiagnosed - can cause significant development and emotional problems for children that have long-lasting effects.
Congenital hearing loss
Congenital hearing loss means it was present in an infant at birth. There are various causes of congenital hearing loss, though they are not always easily identified. There are both non-genetic and genetic factors that might cause hearing loss.
Non-genetic factors that might cause congenital hearing loss include:
- Birth complications, including the presence of herpes, rubella cytomegalovirus, toxoplasmosis or another serious infection, lack of oxygen or the requirement of a blood transfusion for some reason.
- Premature birth. Babies that have a birth weight of less than 3 pounds or that require certain life-sustaining drugs for respiration due to prematurity are at risk for hearing loss.
- A nervous system or brain disorder.
- The use of ototoxic medication by the mother during pregnancy. Ototoxic medications are not usually illicit substances - medications like various antibiotics and NSAIDS can potentially cause damage to the auditory nerve or other hearing structures of the fetus.
- The mother had an infection during pregnancy, including things like toxoplasmosis, cytomegolavirus, herpes simplex or German measles.
- Maternal diabetes.
- Drug or alcohol abuse by the mother or smoking during pregnancy.
|Experts agree that genetic factors cause more than 50 percent of all hearing loss in children, whether present at birth or developed later in life.|
The above causes of congenital hearing loss are all non-genetic factors. However, non-genetic factors account for only around 25 percent of congenital hearing loss. Experts agree that genetic factors - meaning the hearing loss is hereditary - cause more than 50 percent of all hearing loss in children, whether the loss is present at birth or manifests later in life.
Genetic factors that might cause congenital hearing loss include:
- Autosomal recessive hearing loss - This is the most common type of genetic congenital hearing loss - autosomal recessive accounts for around 70 percent of all genetic hearing loss cases. What this means is that neither parent has a hearing loss, but each parent carries a recessive gene that gets passed to the child. Parents are usually surprised when their child is born with this type of hearing loss because people typically aren't even aware they have the recessive gene.
- Autosomal dominant hearing loss - This type of hearing loss accounts for around 15 percent of genetic hearing losses, according to the American Speech-Language-Hearing Association. In autosomal dominant hearing loss, one parent carrying a dominant gene for hearing loss passes it to the offspring. This parent may or may not have hearing loss, but he or she might have other symptoms or signs of a genetic syndrome.
- Genetic syndromes - These include Usher syndrome, Treacher Collins syndrome, Waardenburg syndrome, Down syndrome, Crouzon syndrome and Alport syndrome.
You might have noticed that the percentages don't add up to 100 for genetic and non-genetic causes of congenital hearing loss. This is because some of the time, doctors are not sure why an infant is born with a hearing loss.
Acquired hearing loss
Children can also be affected by acquired hearing loss, meaning it occurs after birth. There are various causes of acquired hearing loss, including:
- A perforated eardrum
- Otosclerosis or Meniere's diseases, which are progressive
- Infections like meningitis, measles, mumps or whooping cough
- Taking ototoxic medications
- A serious head injury
- Exposure to loud noise, causing noise-induced hearing loss
- Untreated or frequent otitis media (ear infections)
- Exposure to secondhand smoke
Transient hearing loss
Transient or fluctuating hearing loss in children is also detrimental to speech and language development. Transient hearing loss can be caused by otitis media, more commonly known as middle ear infection. At least 75 percent of children have had one episode of otitis media by the time they are three years old. This type of infection is very common in children because of the eustachian tube position during childhood. The eustachian tube, which allows for air pressure equalization between the middle ear and the nasopharynx, is smaller and more horizontal during development. Thus, it is very susceptible to blockage by fluids or large adenoids.
Transient hearing loss due to an ear infection can occur when fluid inhibits the vibrations of the tiny middle ear bones, making efficient sound transmission difficult. Thankfully, this type of hearing loss is usually temporary and resolves itself. However, frequent, untreated middle ear infections can cause cumulative damage to the bones, eardrum or auditory nerve, creating a permanent, sensorineural hearing loss.
Hearing loss screening
As mentioned above, hospitals routinely perform hearing screening on infants in the first 24-48 hours after birth. If an infant fails the initial screening, he or she is usually scheduled for a second screening a few weeks later. However, sometimes infants who pass the hearing screening at birth may exhibit signs of hearing loss as they age. If you think your child is having difficulty hearing you, visit your pediatrician right away.
One way to determine if your child’s hearing is developing appropriately is by monitoring important speech and hearing milestones, such as those listed below from the Palo Alto Medical Foundation.
From birth to four months, your infant should:
- Startle at loud sounds
- Wake up or stir at loud noises
- Respond to your voice by smiling or cooing
- Calm down at a familiar voice
From four months to nine months, your infant should:
- Smile when spoken to
- Notice toys that make sounds
- Turn its head toward familiar sounds
- Make babbling noises
- Understand hand motions like the bye-bye wave
From nine to 15 months, your infant should:
- Make various babbling sounds
- Repeat some simple sounds
- Understand basic requests
- Use its voice to get your attention
- Respond to name
From 15 to 24 months, your infant should:
- Use many simple words
- Point to body parts when you ask
- Name common objects
- Listen with interests to songs, rhymes and stories
- Point to familiar objects you name
- Follow basic commands
Older children could also acquire hearing loss that is either permanent or temporary. Here are some things to look for if you think your toddler or preschool-age child might have hearing loss:
- Has difficulty understanding what people are saying.
- Speaks differently than other children her or his age.
- Doesn't reply when you call his or her name.
- Responds inappropriately to questions (misunderstands).
- Turns up the TV volume incredibly high or sits very close to the TV to hear.
- Has problems academically, especially if they weren't present before.
- Has speech or language delays or problems articulating things.
- Watches others in order to imitate their actions, at home or in school.
- Complains of ear pain, earaches or noises.
- Cannot understand over the phone or switches ears frequently while talking on the phone.
- Says "what?" or "huh?" several times a day.
- Watches a speaker's face very intently - many children's hearing loss escapes detection because they are very successful lip readers.
Treatments and interventions
If you notice that your infant or child shows any of the above signs, take him or her to your pediatrician, who can refer you to a pediatric audiologist to have your child's hearing tested. If a child has wax buildup, an ear infection or another problem that is causing temporary hearing loss, the audiologist will take care of the problem or refer you to an otolaryngologist (ear, nose and throat physician) to have the temporary hearing obstruction treated.
Audiologists can perform in-depth behavioral hearing examinations for even very young children (as young as 6 months) who cannot participate in traditional testing procedures. There are several objective tests that infants, toddlers and young children can undergo as well. These tests are painless and non-invasive. After exam, the audiologist will spend time talking with you about your child's hearing ability and recommend an appropriate treatment plan or medical intervention.
Hearing aids are just one kind of device that can help children with hearing loss hear clearly again. There are various advanced models today that offer high-quality hearing assistance, as well as coverings and other devices to ensure that young children don't remove or misplace their hearing aids. There are several models of devices to choose from, including behind-the-ear hearing aids or those that are almost entirely in the ear canal and very discreet.
Cochlear implants are surgically implanted devices that directly stimulate the auditory nerve in the inner ear with electrical stimulation. Cochlear implants also have an external device, and many companies make kid-friendly devices that can be held on with a soft headband. Cochlear implants work for infants and children who cannot benefit from hearing aids.
For children who have had hearing loss that has affected their speech, he or she might need speech-language therapy after getting hearing aids or a cochlear implant to help him or her catch up on speech delays.
Assistive listening devices
Many hearing aid manufacturing companies offer assistive listening devices that are discreet and work well in a classroom situation in conjunction with the child's hearing aid or cochlear implant. Essentially, the teacher wears or has a discreet microphone in front of him or her that transmits his or her voice directly to the child's hearing aids or cochlear implant.
- Hearing Loss in Children, Centers for Disease Control and Prevention, http://www.cdc.gov/ncbddd/hearingloss/data.html
- Causes of Hearing Loss in Children, American-Speech-Hearing-Language Association, http://www.asha.org/public/hearing/disorders/causes.htm
- Conductive Hearing Loss: Causes and treatments, American Academy of Otolaryngology-Head and Neck Surgery, http://www.entnet.org/AboutUs/upload/Causes-and-Treatments-for-Conductive-Hearing-Loss-FINAL-2.pdf
- Maternal Prenatal Smoking and Hearing Loss Among Adolescents, JAMA Otolaryngolgy Head and Neck Surgery, http://archotol.jamanetwork.com/article.aspx?articleid=1699728
- Secondhand smoke and sensorineural hearing loss in adolescents. Arch Otolaryngology Head and Neck Surgery, http://www.ncbi.nlm.nih.gov/pubmed/21768409