Episode 2: What are Important Facts about Hearing Tests?
In today’s ‘What is…series’, I will tackle what you need to know about hearing tests.
I must start by saying that most parents I have encountered at my clinic seem unsure about the necessity of having their child’s hearing tested.
I will usually recommend a hearing test if I encounter a child with delayed speech and/ or language skills as:
- First, it is best practice to check the status of a child’s hearing particularly if they have delayed speech or they are not pronouncing words clearly
- And secondly, hearing is 1 of the pre-requisites to normal speech and language development
Hearing loss & delayed speech
If I don’t recommend a hearing test, I would be negligent because it is a well-documented fact that even a slight hearing loss or fluctuating hearing status can have a dramatic impact on language learning. Check out this blog post to understand the full scope of what a speech therapist does.
After offering this clarification, the follow-on question is usually something of a remark that “oh, my child can hear everything”
To which, I respond, I am not suspecting that your child doesn’t hear completely, but we’re exploring whether they are getting a clear enough sound signal, that they are able to perceive sounds at the different frequencies optimally and that they do not have fluid trapped in their middle ear as is usually the case with a lot of children.
In case you’re interested in learning some fascinating facts about fluid in the ear and how most children are susceptible to getting it, please check out our series on ‘Fluid in the ears’
Let me state some facts about hearing…
Facts about hearing tests
The professional that assesses hearing is called an Audiologist
Your child’s doctor or ENT does not evaluate your child’s hearing, rather the light they may shine into your child’s ear during a check-up is to look at the state of your child’s ear canal/drum…whether it is inflamed, etc.
When a speech therapist requests that you get your child’s hearing tested, the suspicion for most of the cases isn’t that your child is deaf, but rather a question of how well they are hearing and whether they may be experiencing any fluctuating hearing loss, which may be caused by build-up of fluid in the ears.
As stated earlier, it is best practice by a speech therapist to recommend a hearing test for a child presenting with delayed speech.
Even severely profound children CAN perceive sounds such as music, aeroplanes, loud explosions and most at-home hearing tests may not actually be that reliable. Another thing to note that if your child has a hearing loss, they may have their other senses quite acute, which could make up for the hearing loss. They may be very quick with their eyes if you try to sneak up on them to test whether they can hear you, etc.
In order to accurately test your child’s hearing, the audiologist must test the inner ear which is where the hearing organ is housed AND the middle ear as this is usually where any fluid would be trapped. There are various tests that test these specific parts of the ear.
The most popular middle ear test is called tympanometry or very commonly referred to as TYMP. This test assesses the volume of the ear drum, which is an accurate measure of whether or not your child has fluid in the middle ear.
The test is pretty simple and quick. It requires that your child remains very still for the duration of the time it takes the audiologist to insert a probe the child’s ear. The probe is just like the ear thermometers or a cotton tip, but obviously bigger.
So the probe is inserted into the ear, not very far though and it remains there for about 20 – 30 seconds for the audiologist to get a reading. The reading is in the form of a graph, which if there is no fluid, should have a peak. If there was fluid, there would be no peak, it would instead be referred to as a flat tympanogram or type C.
What is ideal is a type A.
Check out a Tympanometer below
Tests for assessing the inner ear
There are various tests for assessing the inner ear:
- Behavioural tests- PTA. PTA stands for puretone audiometry It is also called air conduction testing since the sounds go through your outer and middle ear. This test helps find the quietest sound your child can hear at different pitches, or frequencies. The audiologist can either put earphones on in order for the sounds to go to one ear at a time or the sounds can be administered FREE FIELD meaning the sound is just administered in the sound booth and the audiologist looks for a reaction from the child that they heard the sound. With free field, Audiogram
- Play Audiometry
- ABR- Automated brainstem response test- tells us how the inner ear, called the cochlea, and the brain pathways for hearing are working. The test is used with children or others who cannot complete a typical hearing screening. The ABR can also be recommended if your child’s symptoms might be due to hearing loss in the brain or in a brain pathway
There is a condition called auditory neuropathy- where usually what would cause a hearing loss which is as a result of the inner ear not functioning properly would be the loss of hair cells in the hearing organ, but in the case of auditory neuropathy, the hair cells within the cochlea are present and functional, but the sound information is not faithfully being transmitted to the auditory nerve properly.
Every organ in the body or every motor action or muscle action has to be communicated to the brain through nerves in order for that function to be properly executed.
So an ABR would also be used to ascertain that the nerve that communicates sound to the brain- the auditory nerve is working properly.
ABR tests are also used when a child is being assessed for eligibility to have a cochlear implant as if the nerve is not communicating between the cochlear and the brain, then even with a cochlear implant, that child would not hear if there is nerve damage or auditory neuropathy.
I really hope I am being clear. Please feel free to let me know in the comments. Also feel free to pause, rewind as many times if all this doesn’t immediately make sense.
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