After working as a chemist at a biotechnology company, I enjoy writing about science, travel, and gardening.
Can My Baby Hear?
In the United States, a newborn hearing screening test is required before a baby is released from the hospital. While most babies pass the newborn screening test, some infants will score a "refer" on the screen.
Not every infant who scores a "refer" will have a hearing problem. Some infants have extra fluid from birth, which interferes with the test results. Sometimes, the test is faulty, giving a "false positive" result. The point of the newborn hearing screen is not to diagnose infants with a permanent hearing loss, but to identify those infants which need further testing.
It is absolutely vital to follow up on any hearing screening test which results in a "refer." Often, the hospital will retest the baby, after a period of time, to see if ear fluid was causing any problems with the test. If the baby refers on a second screening test, further testing will be required.
Infants who refer on the newborn hearing screen will be referred to an audiologist for a diagnostic auditory brainstem response test (ABR), otoacoustic emissions test (OAE), tympanometry, and bone conduction testing. These tests are painless and give a very reliable estimation of the baby's hearing ability. If a hearing problem is found, the audiologist will determine if the hearing loss is due to a potentially correctable cause (a conductive hearing loss) or if the hearing loss is not correctable (a sensorineural hearing loss).
The diagnosis of hearing loss in infants will be made by an Ear, Nose, and Throat physician (otolaryngologist) after a full evaluation by an audiologist. Recommendations for amplification (such as hearing aids or a cochlear implant) and referral to an Early Intervention program will occur quickly after the diagnosis of permanent hearing loss is made.
If your baby refers on the newborn hearing screening test, don't despair. While many babies will not have a permanent hearing loss, it is important to follow up on all the required testing. Early intervention and amplification are vital if a child is suspected of having a permanent hearing loss.
Follow Up Testing
Once a baby has referred on the newborn hearing screening program, the child's pediatrician will write a referral to an audiology center capable of handling diagnostic newborn hearing tests. The tests that will definitively assess a baby's hearing ability include the auditory brainstem response (ABR), otoacoustic emissions (OAE), bone conduction testing, and tympanograms.
Auditory Brainstem Response Waveforms
The Auditory Brainstem Response
An ABR test is completely painless, though the test does require a sleepy baby. Often, parents will be instructed to keep the baby awake for a few hours prior to the test, so that the child will fall asleep when it is time to run the hearing test. Infants older than 4 months will probably have to be lightly sedated for this test (movement can interfere with the test results).
This test uses electroencephalogram (EEG) readings from the auditory center of the brain. Tones are played into the sleeping baby's ear, and the audiologist looks for a neural response from the baby's brain. Using this method, the technician can determine the baby's estimated hearing thresholds at each level.
Parents can be told about the baby's hearing ability shortly after the test is completed. If a hearing loss is present, this test will diagnose the specific level of hearing loss (mild, moderate, severe, or profound). In addition, this test is able to diagnose auditory neuropathy (auditory dyssynchrony), which may have a different course of treatment than traditional hearing loss.
The ABR test may give an abnormal response if fluid or another mechanical obstruction to sound is present. For this reason, it is important to obtain bone conduction measures and an accurate tympanogram as part of the comprehensive hearing evaluation.
An ABR Screening Test
Otoacoustic Emissions (OAE) are tested to determine the presence of healthy cochlear hair cells: the presence of healthy hair cells indicates a healthy inner ear. The most common OAE test performed on young infants is called the transient evoked otoacoustic emissions test. A healthy cochlea will send back an "echo" of the tone sent to the ear (this is the otoacoustic emission). A tiny microphone can pick up the emission, verifying the cochlea is healthy.
OAE have limitations: if there is middle ear fluid from the birth process, or if the middle ear is otherwise compromised (middle ear bone abnormalities), the OAE will not be present. In addition, children with auditory neuropathy will have present OAE, as the cochlea is not affected by this condition. Children with mild hearing losses will sometimes have present OAE.
It is important to obtain a full hearing evaluation, as assessing the OAE will clarify the type of hearing loss (if present), or help confirm the presence of normal hearing.
A tympanogram is a fast, easy test which emits a small amount of air pressure against the baby's eardrum. If the eardrum is "stiff" and unresponsive to the pressure, there may be fluid in the middle ear space. This is an important part of diagnosing the type of hearing loss, if present. Hearing loss caused by fluid in the middle ear space is reversible with the placement of tympanostomy tubes (also known as "ear tubes" or "grommets"). An Ear-Nose-Throat physician (ENT) will fully evaluate and treat this condition if present.
If the baby has a normal tympanogram, then fluid is not likely to be the cause of any detectable hearing loss.
Bone Conduction Testing
Bone Conduction testing determines whether the hearing loss is caused by the middle ear (which is generally correctable), or the inner ear (which is permanent). This testing bypasses the middle ear system, by vibrating against the mastoid bone (or another area of the baby's head). This gentle vibration sends sound directly to the inner ear: if there is still a difficulty with hearing the sound, then the hearing problem resides in the inner ear (cochlea).
If the hearing level is normal with the bone conduction testing, then the hearing problem is caused by the middle ear: there is either fluid, or the middle ear bones are not working correctly.
Sometimes, a baby has a mixed loss. In this case, the bone conduction testing will be better than the sound received through the air, but will not reach normal levels. This means the hearing loss is caused by a combination of inner ear problems (cochlear hair cell loss) and mechanical sound transmission issues (middle ear bone malformations, fluid, or bone stiffness).
It is vital to obtain bone conduction testing on every baby, to verify the exact cause of the hearing loss.
|Bone Conduction Results||Air Conduction Results||Type of Hearing Loss|
Bone Conduction Results Explained.
This content is accurate and true to the best of the author’s knowledge and does not substitute for diagnosis, prognosis, treatment, prescription, and/or dietary advice from a licensed health professional. Drugs, supplements, and natural remedies may have dangerous side effects. If pregnant or nursing, consult with a qualified provider on an individual basis. Seek immediate help if you are experiencing a medical emergency.
Leah Lefler (author) from Western New York on June 14, 2015:
It is so critical to have follow-up testing performed when a baby refers on the newborn hearing screen. I do wish the hospital nurses would refrain from saying, "Oh, it is likely to be fluid," since in some cases a permanent hearing loss does exist. My son is now almost 8 years old, iv, and I am very grateful for the newborn hearing screening program. He plays piano, has the best language and spelling scores in his mainstream class, and is a happy and healthy little boy.
iv on May 26, 2015:
This is definitely the best article on this subject and believe me, I have read so many since my daughter "failed" one ear on the newborn ABR.
I also agree with you Leah, I disagree with the approach of blaming fluid for the results thus delaying further testing. It is best not to speculate or give parents a false sense of comfort, it is best to do all tests and make decisions.
Leah Lefler (author) from Western New York on September 29, 2014:
Kierstin, there are certainly false positives on the newborn hearing screening. It is better to have a false positive than a false negative - so thank goodness newborn hearing screening exists! I know several people who were told their baby didn't pass because of fluid, only to find out their child truly did have a hearing loss - and they lost precious time with early intervention due to the idea that the "refer" result was due to a restless baby. If in doubt, it is always best to have a full, diagnostic ABR performed. There is no doubt (or little doubt) with that test!
Kierstin Gunsberg from Traverse City, Michigan on September 16, 2014:
Great article! My daughter failed her newborn screening last year on a technicality-- she passed in both ears but on separate occasions. In total she had it four times before she finally passed and only after a lot of coaxing and comforting on my part.
What parents need to know about the newborn screening is that babies will not pass if they're wiggling, crying, have fluid from birth still trapped in their ears, or if they're simply thinking too much about something!
Leah Lefler (author) from Western New York on January 08, 2013:
Thanks, Au fait - we were searching for information when our son was born and failed the newborn hearing screen. The test is extremely valuable as it allows children to obtain a diagnosis early in life and get fitted for hearing aids. Our son is now five years old, in Kindergarten, and reading. Early intervention was extremely successful for him!
C E Clark from North Texas on January 08, 2013:
This is great information! Well written and covering pretty much everything. Thankfully my own baby (now 24 years old!) didn't have a hearing problem, but this is information that will be invaluable to people whose baby does have hearing issues.
I've noted you have more hubs on this issue so I'm hoping more people who are searching for information and help will find them.
Voted up, useful, and will share with my followers!
Leah Lefler (author) from Western New York on January 27, 2012:
Dan, that is an excellent video! The states all differ in the implementation of the newborn metabolic disorder screening tests, and I wasn't aware that parents could pay for supplemental screening. I love the way some hospitals are doing the heel stick at the mother's bedside, while she's feeding her child. Most parents aren't aware that a hearing test or heel stick was even done! Our own little boy "referred" on the newborn hearing screening program and we are SO fortunate that he was caught by the test. At the age of 4 1/2, he is age appropriate for speech and language. The screening tests are worth their weight in gold!
Dan on January 26, 2012:
Really comprehensive...pleased that you are bringing needed attention to the issue of newborn screening. You really provide a detailed overview of newborn hearing screening tests and there's surprisingly not as much info online as one might imagine. You really bring clarity to the issue of when a newborn refers which can be a frightening thing for new parents. I thought I would share this video from the Save Babies Foundation to add to the discussion