Parents, it is certainly not easy to simply assess whether your little one has normal hearing. One way to do this is to conduct a test.otoacoustic emissions(OAE).
This test is mostly intended for babies and children. So how is this test done?
Definition of Otoacoustic Emissions
The human ear consists of three parts, namely the outer, middle and inner ear.Otoacoustic emissionsitself means the sound produced by a small part of the cochlea when stimulated by a soft clicking sound.
When sound stimulates the cochlea, the outer hair cells vibrate. The vibrations produce a barely audible sound that echoes back to the middle ear. This sound is what is measured in the OAE test.
This test can be done for your baby, especially since he or she cannot yet respond to other hearing tests like adults. If your child has normal hearing, he or she will produce OAEs. If the hearing loss is greater than 25–30 decibels (dB), your child will not produce these very soft sounds.
Types of Otoacoustic Emissions Examination
To check the condition of your baby’s middle ear, this can not only be done with one type. There are at least four types of OAE, namely as follows:
- Spontaneous otoacoustic emissions(SOAEs) – Sounds emitted without acoustic stimulus or spontaneously.
- Transient otoacoustic emissions(TOAEs) or transiently evoked otoacoustic emissions- Sounds emitted in response to acoustic stimuli of very short duration. The sounds may sound like “clicks” but may be bursts of tones.
- Distortion product otoacoustic emissions(DPOAEs) – Sounds emitted in response to 2 simultaneous tones of different frequencies.
- Sustained-frequency otoacoustic emissions (SFOAEs) – Sounds emitted in response to a continuous tone.
Otoacoustic Emissions Test Function
Parents , if you are considering doing this test on your child, of course you must first know what the functions of this OAE test are. In general, this test functions to detect the presence or absence of hearing loss in babies.
This test can also show if there is a blockage in your outer or middle ear. If there is a blockage, no sound can get through to the inner ear. This means there will be no vibrations or sounds coming back.
The information obtained from this test can then be used to:
- Hearing screening (especially in neonates, infants, or individuals with developmental disabilities)
- Estimating partial hearing sensitivity within a limited range
- Differentiate between the sensory and neural components of sensorineural hearing.
- Test for functional (feigned) hearing loss. Information can be obtained from patients who are asleep or even comatose because no behavioral response is required.
Quoting fromNationwide Children’s, it is important for this hearing test to be performed by a pediatric audiologist. He or she is a specially trained doctor who has expertise in treating children, particularly identifying hearing loss in children.
A pediatric audiologist will be able to decide which tests are important to perform, and complete them with accuracy and efficiency. If a hearing loss is identified, the pediatric audiologist will provide you with information about hearing loss, communication options, and resources.
Otoacoustic Emissions Test Steps
There is no need to worry if your child is scheduled for a test.otoacoustic emissions, because of course this examination is carried out by an expert. Here are the steps of the OAE test that you need to know and prepare:
- During the test, your child is not allowed to fall asleep.
- Everyone in the room must sit still and not make a sound.
- The healthcare provider will place a soft foam or rubber tip in your child’s ear. Your little one will then hear soft sounds through the soft foam or rubber tip.
- The person taking the test can see the results on the monitor screen.
- Your child will not feel anything during this test.
- This test only takes a few minutes.
Otoacoustic Emissions Test Results
After your child has completed the test, the examiner will then view the results on the monitor screen. In general, the results indicate whether or not there is a disorder in the child’s ears. Here is the explanation:
- Current OAEs are consistent with normal to near normal hearing.
- Absent OAEs may be a sign of a problem. This could be hearing loss, earwax, fluid or infection in the middle ear or a defect in the inner ear. This suggests that further testing is needed to find out why OAEs are absent, and to rule out the possibility of hearing loss.
Factors That Can Affect Otoacoustic Emissions Testing
There are several factors that can affect the running of the OAE test and also its results. These factors include:
Nonpathological Problems That May Cause Absence of OAEs
There are several nonpathological problems that can affect the results of the OAE test, including:
- End placementprobebad or broken seal: Most modern equipment alerts doctors to the possibility of these problems.
- Standing waves: Most modern equipment alerts the doctor to the possibility of this condition.
- Earwax that blocks the canal or obstructs itport probe.
- There is debris and foreign objects in the external ear canal.
- Vernix caseosain neonates: This usually occurs immediately after birth.
- Uncooperative patient: Usually, the recording is not obtained properly.
Pathological Problems That Can Cause Absence of OAE
Of course, some pathological problems, especially those in the child’s ear, can affect the test and the results. Here are some of the medical problems in question:
Problems in the Outer Ear
Pathological conditions that may have an impact include:
- Stenosis
- Otitis externa
- Cyst
- Abnormal middle ear pressure
- Tympanic membrane – Eardrum perforation (PE tube does not always prevent good recording.)
Middle Ear Problems
If there are problems in the middle ear, the following may be the reason why the OAE test results cannot be obtained. These problems include:
- Otosclerosis
- Middle ear disarticulation
- Cholesteatoma
- Cyst
- Bilateral otitis media: To record OAEs, the cochlear response must be able to travel efficiently through the middle ear and tympanic membrane to the recording microphone in the ear canal. Even with normal cochlear function, OAEs are generally absent in the presence of otitis media.
OAE testing is best done after the otitis media has resolved. If the patient cannot be tested later, when the otitis has resolved, there is no harm in trying to record OAEs.
If OAEs are present (as in a very small percentage of patients with otitis media), this information can be useful. If they are absent (as in most patients with otitis media), no conclusions about cochlear function can be drawn.
Cochlea
This is the organ of hearing that functions to send messages to the auditory nerve and brain. The following problems that occur in the cochlea can affect OAE:
- Ototoxic drug exposure or noise exposure (including music): OAE changes may precede threshold changes in the conventional frequency range.
- Other cochlear pathologies
Conditions That Do Not Affect OAE
These conditions include:
- CN VIII pathology: If CN VIII pathology also affects the cochlea (eg,vestibular schwannomawhich reduces the vascular supply of the cochlea), OAEs will be affected.
- Central hearing loss
Conditions that Give Rise to Abnormal OAEs and the Threshold of Normal Behavior
These conditions include:
- Tinnitus: OAEs may be abnormal in the tinnitus frequency region.
- Excessive noise exposure (can cause increased or decreased amplitude): No clear correlation with noise-induced threshold changes.
- Ototoxicity
- Vestibular pathology
Conditions That Give Rise to Normal OAEs and Abnormal Behavior Thresholds
Here are some of them:
- Functional hearing loss
- Attention deficit
- Autism
- Possibly, inner hair cell damage but outer hair cells are normal (reported for animals but no reports in humans)
- Auditory neuropathy: This includes central auditory nervous system dysfunction and CN VIII auditory dysfunction.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2)
A study found that in asymptomatic people infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19 disease, high-frequency pure-tone thresholds and OAE amplitudes were significantly worse than controls, suggesting that the infection damages cochlear hair cells.
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That is the explanation regarding the testotoacoustic emissionsand its uses. Hopefully this article is useful.
Republished with permission from theAsianParent Indonesia
