Testing a baby's hearing through newborn hearing screening programs is the best way to detect a hearing loss as early as possible. If this is not done, it is quite often the parent that begins to suspect that something is not right. But it can sometimes be difficult to tell if a child has difficulty hearing. Children with a hearing loss often learn to compensate for the lack of audible signals by being more sensitive to other informative signals such as changes in light as a door is opened or closed, vibrations in the floor, and movements of air. Their responses can seem quite normal, making the loss difficult to detect.
If you suspect that your child has trouble hearing, trust your intuition and make an appointment to see an audiologist or your family doctor to arrange a full audiometric evaluation. A child is never too young to have their hearing evaluated. Studies have shown that the sooner a child with hearing loss is fit with hearing aids, the better their language skills will develop. A hearing test is a simple, painless way to be sure that your child is getting the most out of the world around him or her.
Signs of hearing loss
Children develop at their own individual pace, so while of none of the following signs is a sure indication of a problem, any of them could mean that your child is missing important aural information:
- Failure to startle at loud sounds
- Inability to locate the source of a sound – i.e. turning the head towards the person speaking. Children with normal hearing will usually do this at 5 or 6 months of age
- Generally requiring louder sound levels in order to function – sitting too close to the TV, turning up the volume, frequently asking "what" when spoken to, not responding when called
- Babbling ceases or changes to more high-pitched screaming sounds at the age of 6 – 8 months
- Lack of normal responses to sounds – does not respond to his or her name by 6 months of age
- Failure for babbling to evolve into recognizable speech and finally to words during the second year
- Failure to respond to simple commands as "bring daddy the ball" by 1 year of age, unless the child is looking directly at you and seeing your body language
- Withdrawing from social contact and perhaps "acting out" aggressively. This can indicate frustration over the constant misunderstandings resulting from hearing loss
- Frequently misunderstanding spoken directions
If you suspect your child has a hearing loss or if there are physical or medical conditions of the ear which concern you, it is a good idea to schedule a hearing test with an audiologist who routinely works with children. An audiologist accustomed to testing adults may not have the necessary equipment to properly assess hearing loss in children.
Children of any age – even newborns – can have their hearing tested using a variety of methods. The method used depends on the age and maturity level of your child. These tests do not cause your child any pain or discomfort.
What to expect at the hearing test appointment
Your hearing health care professional will gather as much information as possible to help determine the existence or cause of a hearing loss. Questions pertaining to family, environment, illness and pregnancy will be asked. If a hearing loss is discovered, this information can be helpful in determining proper management and rehabilitation strategies.
Tests that do not require active participation of the child:
An otoscope is a light-emitting instrument that enables the audiologist to clearly visualize the ear canal and eardrum, revealing any possible physical abnormalities contributing to a hearing loss.
- Otoacoustic emissions
This test is usually performed on a calm or sleeping child. (It is very fast and is often done in the neonatal unit of the hospital shortly after your child's birth as part of a newborn screening program. See also ABR below.) This test measures activity generated by the small hair cells within the inner ear following stimulation by sound.
- Auditory Brainstem Response (ABR)
This test measures brain waves following stimulation by sound. It takes somewhat longer than the Otoacoustic emission test, but the results can be useful when fitting your child with a hearing aid. Since it is a longer test, it is best performed when the child is asleep, either at naptime or, if necessary, under light sedation.
- Immittance measures
Immittance testing assesses the integrity of the middle ear by measuring eardrum mobility and middle ear pressure following a change of pressure in the ear canal. It is very helpful in the diagnosis of middle ear infections.
This testing may also be used to record the acoustic reflex which occurs following the presentation of certain loud sounds. It produces a tightening of the eardrum and is a natural protection against loud sounds. If the reflex is absent or elevated (ie – only produced after presentation of an extremely loud signal), it may indicate a hearing problem. This is another extremely rapid test that does not require active participation of your child.
Tests that require active participation of the child:
Your child will need to be alert and be able to focus on simple tasks, so be sure she is well rested and prepared to interact with one or two friendly adults.
- Pure tone audiometry
Pure tone audiometry determines the softest volume at which your child can hear a variety of sounds. This level is also referred to as the hearing threshold. An accurate measure of the hearing threshold is important for the process of fitting a hearing aid, if necessary.
During testing, sounds are delivered in one of three ways: through headphones, through small earphones that fit into the ear canal (insert earphones), or through loudspeakers in the testing booth. Your child will have the task of indicating when she hears the sound.
The method used will depend on the age and maturity of your child. Very young children are usually tested while sitting on the parent's lap. Sounds are delivered through loudspeakers. When the sound is presented, the child should look at the speaker which presented the sound. There is usually a toy on top of the speaker which is animated by the audiologist to reinforce the child's behavior of looking at the speaker when she hears the sound. This method is useful for obtaining thresholds, but it cannot give the audiologist ear specific information, because you cannot be sure which ear is hearing.
In older children, the child is instructed to respond to the sound by completing part of a game (i.e. fitting a piece in a puzzle). The sound can be delivered through headphones or insert earphones. The advantage to this method is that each ear can be tested individually. Once a child has reached a certain age, he or she can respond as an adult by pressing a button or saying "yes" each time a sound is heard.
- Speech audiometry
Older children can be tested using speech audiometry. It is similar to pure tone audiometry, but the sounds presented are actual words. The goal is to determine the hearing threshold to detect and recognize speech. Again, the sounds can be presented through speakers, headphones, or insert earphones in a manner identical to that indicated for pure tone audiometry.
A young child would be expected to turn his head towards the speaker emitting the sounds. An older child would be expected to repeat words or to point to a picture in a book or to his eyes, nose, etc.
Speech would also be presented at a conversational level to determine if speech is properly understood by your child.
The results of the audiometric tests described above are entered on an Audiogram. This is an important tool in evaluating the hearing loss and fitting a hearing aid.