A ‘diagnostic hearing test’ is also known as a ‘complete’, or ‘full’ hearing test. It is an in depth assessment that looks at the function of your outer, middle and inner ears and takes approximately 30 minutes.
We review your history of ear disease, take a note of any ear or hearing symptoms you are presenting with, and any symptoms you may have had in the past. It is helpful for us to know about family members who have hearing loss, any surgery you may have had in the past, and to understand your history of noise exposure.
We look in your ear with a magnifying tool called an otoscope to check your ear canal and tympanic membrane (ear drum). This part of the assessment determines first if the ear canal is clear of obstruction, and if so, allows the audiologist to inspect the anatomy of the canal and tympanic membrane. If there is a perforation or grommet in the tympanic membrane this will be identified. Holes in the eardrum, along with fluid behind the eardrum, and ear infections can also be picked up in this manner.
Tympanometry – A small plug is placed firmly in each ear canal. A speaker within the plug emits a low humming sound. By changing the pressure within the ear canal, and measuring how loud the humming sound is as we sweep across the different pressures, we can identify how much your ear drum is moving, and whether your middle ear (the space behind the ear drum) is well equalized. This test can help identify medical causes for hearing difficulties such as fluid or infection behind the ear drum (glue ear) or if there is a hole in the ear drum (perforation).
Acoustic Reflexes – We deliver a loud sound through the plug and measure whether a small change to the stiffness of the ear drum can be detected that is synchronised to the delivery of the sound. If noted, the change is stiffness is a result of the contraction of a small muscle in the middle ear – this is called an acoustic reflex. We measure acoustic reflexes to check the pathway of the sound from the ear to the brain and back to the ear (the ipsilateral acoustic reflex) or to the opposite side (the contralateral acoustic reflex). When we see particular patterns of acoustic reflexes being absent it raises suspicion of problems with the hearing or facial nerves.
PURE TONE AUDIOMETRY
All of the hearing assessment are conducted in a sound treated booth. We use a testing booth so that ambient noise doesn’t affect your hearing results.
Air Conduction Testing – A small, soft foam plug is placed into your ear canal, and will expand to deliver additional reduction of background noise. You will hold a button and we will ask you to press it when you hear a beep. Some people find this part a bit difficult – when you are responding to the very smallest sounds you can hear it can be difficult to decide whether you have heard a beep, or just imagined it! During the test we measure the quietest sounds you can hear at frequencies from 250 Hz to 8000 Hz (from the deeper sounds to the sharper high frequency sounds). We plot these results on a graph called an audiogram. Frequency is recorded on the x axis, while the intensity (loudness) is measured on the y-axis. We measure the overall hearing of each ear, and can let you know whether your hearing is normal, or whether there are some sounds that you don’t hear well.
Bone Conduction Testing – A metal headband with a small vibrating box is placed on the mastoid bone behind the ear. The vibration of the box sends sounds directly through the bone to the cochlea or inner ear, bypassing the ear canal and middle ear. As with the air conduction testing, you will be asked to respond to a beep. You may not be able to decide whether you detect it on the right ear or the left ear (which doesn’t matter). When there is a significant difference in hearing between the ears we need to deliver a masking signal to the better hearing ear. The masking signal allows us to determine which ear you are hearing the sounds on. The results of the bone conduction testing will help us understand what type of hearing loss you have (sensorineural or conductive, or both). Sensorineural hearing loss may indicate damage to the nerve or cochlea, while conductive hearing losses generally reflect damage of the eardrum or middle ear. Knowing whether your hearing loss is sensorineural or conductive allows us to recommend treatment options.
Speech audiometry testing is carried out to help us identify distortion within your auditory system. We also use the speech test as a cross check of your hearing thresholds.
A list of phonetically balanced words is played through the earphones which you are then asked to repeat. The words are presented at a comfortable level where you are expected to get 85-100% correct and also at a level where you can only accurately identify approximately 50% of the presented words.
At completion of the diagnostic hearing test Emma or Sandra will explain the test results and provide you with advice. In some cases referral to your GP or to an Ear, Nose and Throat specialist, for further medical investigation, will be recommended. The discussion may also cover potential benefits from the trial of hearing instruments. You will receive a written report on the results, even if a referral is not necessary.
A diagnostic hearing test costs $105. If you have medical insurance, depending on your level of cover, you may be able to claim this back. If you would like to speak to one of our team about this test please contact us here.