COMPLETE HEARING TESTS
Your hearing care professional will perform a complete hearing evaluation to establish the health of your hearing system. Your medical history will be discussed and you may be asked questions related to noise exposure, medications you’re taking, past surgeries, and possible diseases.
You will then be given a series of test to check for hearing loss including:
- Pure Tone Test
- Speech Discrimination Test
- Most comfortable listening level test (MCL)
- Uncomfortable loudness level test(UCL)
- Bone Conduction Test
- Otoacoustic Emissions (OAEs)
The results of your hearing test will determine where your hearing loss is originating from (outer, middle, or inner ear) and how severe it is (mild, moderate, severe, or profound).
PURE TONE TEST
A pure tone test checks for the lowest tones you can hear at various pitches, beginning from low to high.
You will be seated with earphones in a soundproof room, while the hearing specialist is seated outside to operate the auditory equipment. You will then be tested to see if you can hear a range of pitches, and respond to them by raising your finger or hand, or pressing a button. The earphones gather information from each ear, while a graph known as an audiogram records the results.
For young children, more play-oriented tests may be employed, including visual reinforcement audiometry (VRA) and conditioned play audiometry (CPA).
BONE CONDUCTION TEST
A bone conduction test sends tones to a device placed behind your head. This test assesses your inner ear’s hearing ability by allowing sounds to bypass your external auditory canal and middle ear through your skull. This allows it to more accurately examine your inner ear’s hearing ability without having the external auditory canal and middle ear affecting results.
The results of your test are revealed on an audiogram. It may show that your hearing is normal or that there’s impairment. If there is hearing loss, it will indicate the severity (mild, moderate, severe, profound) and the type (conductive, sensori-neural, mixed).
The speech discrimination test measures how well you can hear speech when it’s loud enough to comfortably hear. This is known as the Most Comfortable Level (MCL). Your hearing specialist will read or play a list of words given through headphones and you will repeat back what you hear.
Your speech discrimination score is measured in percent – 100% meaning you can hear and comprehend everything said to you, and 0% meaning you can’t hear and understand anything said, regardless of the loudness level. Scores below 90% point to problems with word recognition, while a score below 50% indicates poor word discrimination.
UNCOMFORTABLE LOUDNESS LEVELS
This test determines the stage where sounds become uncomfortable to hear for a person. You will be seated in a quiet room where you will be given headphones to wear and a handset to press. Your hearing specialist will play a series of sounds through your headphones which will become gradually louder. The moment the sounds become uncomfortably loud, you press the button on the handset and the test will stop.
This test should take 5 to 10 minutes to complete. Before the test, you should inform your hearing specialist if you’ve had tinnitus in the past.
Tympanograms assess problems in the middle ear by measuring the stiffness of the eardrum. It checks for fluid and negative pressure in the middle ear, and possible problems with the ossicles and tympanic membrane.
The device is placed in your ear and a small amount of pressure is applied inside the middle ear. The tympanogram records the results on a graph.
During the test, it’s important to remain still since any movement can change the pressure in the middle ear and affect the test results. You may also feel some slight discomfort but this is normal.
ACOUSTIC REFLEXES AND DECAY
This test checks to see whether a reflex contraction can be maintained during a short stimulation. A continuous tone is presented for 10 seconds, which is 10dB beyond the acoustic reflex threshold. The results of the muscle response are recorded.
If the magnitude of the reflex response stays contracted for the 10 second duration, the test is negative for reflex decay. However, if the reflex response drops more than 50% during that time, the test is positive for reflex decay.
EUSTACHIAN TUBE DYSFUNCTION
The eustachian tube is a thin tube that joins the middle ear to the back of the nose. It’s approximately 3-4cm long in adults. The tube’s main function is to equalize the air pressure inside the eardrum and outside of it. This allows the eardrum to function and vibrate properly, so we can hear. The tube is usually closed, but opens when we swallow, yawn or chew. This allows air to flow into the middle ear and drain any secretions or waste.
Eustachian tube dysfunction happens when the tube doesn’t open properly or is blocked. This prevents air from getting into the middle air, so the pressure from outside the eardrum becomes different than inside the middle ear. This can cause muffled or dull hearing, ear pain, ringing and dizziness. Symptoms are often caused due to a cold and usually go away within a week or two.
OTOACOUSTIC EMISSIONS (OAES)
Otoacoustic Emissions measure the inner ear’s hair cell function. An emission is a sound produced within the cochlea when it is stimulated, which causes the outer hair cells to vibrate. The vibration creates a very soft sound that causes the cochlea to echo in response to the sound. Small probes are inserted into the ear, which measures the sound.
People with a hearing loss greater than 25-30 db cannot produce these soft sounds. This test is often used to detect deafness for newborn babies and hearing loss for adults.
HEARING IN NOISE TEST (HINT)
This test measures how well you can hear speech in quiet and noisy settings. This is known as your sound to noise ratio (SNR). You will repeat sentences that you hear in both a quiet environment and in a noisy one. A higher SNR indicates that you may have trouble hearing in noise.
The test consists of 4 conditions:
1 – Sentences are presented noise-free
2 – Sentences are presented with competing noise in front of you
3 – Sentences are presented with competing noise to the right of you
4 – Sentences are presented with competing noise to the left of you
You are given either a ‘pass’ or a ‘fail’ for each condition. Other than determining your SNR, the HINT test is useful for finding suitable solutions for hearing loss.
VIDEO OTOSCOPIC EXAMINATION
This examination involves using an instrument called an otoscope to look inside the ear. An otoscope transmits a bright light into the ear canal and has a tiny video camera which relays images to a TV screen. It also has a working channel that can remove debris within the ear by flushing or drying it out.
A video ocoscope allows the hearing specialist to better examine the ear than a hand held ocoscope. The instrument is especially effective for deep ear flushing, flushing behind a ruptured ear drum, and detecting and biopsying tumors in the ear canal.