About hearing tests
Learn about the different types of hearing tests you might have with a hearing specialist, and how the results are plotted on an audiogram.
Hearing tests are key to understanding the nature of your hearing loss, and the first step to improving your hearing and quality of life. If you think you have a hearing loss, you should make an appointment with an audiologist or other hearing specialist to have it tested. They use a series of tests to assess the type and degree of hearing loss you are experiencing. With this information, your hearing specialist can then recommend the best treatment options for your hearing needs and lifestyle. Following is an overview of the different hearing tests used to diagnose hearing loss in adults – with air conduction, bone conduction and speech recognition tests the most common.
Pure tone air conduction testing uses a range differently pitched beeps, called pure tones, to test your hearing capacity across the full range of different frequencies. When listening to pure tones, the measurement is called pure tone audiometry.
Bone conduction testing measures the sensitivity of the cochlea using a small vibrator on the mastoid bone behind the ear. Sounds presented this way travel through the bones of the skull to the cochlea and hearing nerves, bypassing the middle ear.
Speech recognition testing evaluates your ability to understand words and sentences spoken at an everyday listening level but can vary for different types of tests. It can also determine your speech recognition threshold, or the faintest speech that you can hear half of the time. As people with hearing loss often have difficulty understanding speech in background noise, speech testing may be done in a quiet or noisy environment.
Your hearing specialist may also use other tests to get a more detailed understanding of your hearing loss.
A number of middle ear tests don’t test hearing but provide information about how the middle ear is functioning. Tympanometry measures how well the tympanic membrane (ear drum) is moving. This test helps detect fluid in the middle ear, a perforated eardrum, or wax blocking the ear canal. Acoustic reflex measures look at the volume at which the tiny muscle in the inner ear contracts, to help determine where hearing loss is happening. Static acoustic impedance measures the physical volume of air in the ear canal, which is useful in diagnosing a perforated eardrum or checking the openness of ventilation tubes.
Auditory brainstem response (ABR) testing is used to diagnose hearing loss in the brain or brainstem, using electrodes that record brain wave activity in response to sound. The test may be performed if you have symptoms of a hearing loss in the brain or auditory nerve pathway.
Otoacoustic emissions (OAEs) testing measures the vibrations given off by the inner ear when the cochlea is stimulated by a sound. This testing can be used to test the function of the cochlea and other parts of the ear, including the auditory nerve.
Understanding an audiogram
The results of your hearing tests are mapped onto a chart called an audiogram, which gives a visual overview of your hearing loss and its impact on your everyday life. An audiogram shows the lowest levels that you can detect different sounds, from low to high frequencies. Decibels (dB) measure the volume or intensity of sound, while hertz (Hz) measures pitch or frequency.
Normal conversation generally takes place within the 20 to 60 dB range - commonly referred to as the ‘speech banana’ because of the shape it makes on an audiogram. The audiogram also shows where other everyday sounds fall in relation to the speech banana. For example, the sound of a bird chirping is softer and higher-pitched than most normal conversations, while the sound of a dog barking is louder and lower-pitched.
Your results are plotted as two lines (right ear and left ear). The sounds that lie above the lines are what you have difficulty hearing, while the sounds below are what you can hear. Some people may have trouble hearing tones in the higher frequencies (2,000 – 8,000 Hz) while others may have trouble hearing tones in the lower frequencies (125 – 1,000 Hz). The audiogram will also be able to tell you the degree of your hearing loss―mild, moderate, moderately severe, severe, or profound.
Diagnosing the different types of hearing loss
Your hearing specialist uses bone and air conduction tests to diagnose the type of your hearing loss.
If the air conduction test shows hearing loss, you will need bone conduction testing to find out more about the source of the problem.
If the air conduction test shows hearing loss, but the bone conduction test does not, you have conductive hearing loss, resulting from sound blockage in the middle or outer ears. If the bone conduction test shows the same results as the air conduction test you have sensorineural hearing loss, resulting from a loss of sensitivity in the cochlea or hearing nerve.
If your bone and air conduction hearing thresholds are the same, it suggests you have no sound blockage in the outer or middle ear. This means If your bone conduction hearing thresholds are normal, but you lose hearing with air conduction, your cochlea is likely to be normal and healthy. In this case you are likely to have a conductive hearing loss, resulting from sound blockage in the middle or outer ears.
You may also have a mixed hearing loss, with both sensorineural and conductive hearing loss present.
Degrees of hearing lossThe following chart defines each degree of hearing loss.1
|Degree of hearing loss||Softest sound able to be heard (in decibels)||Frame of reference|
|Mild||26 to 40 dB||Able to hear the loud or more intense vowel sounds, but may miss some of the softer consonant sounds. People with a mild hearing loss may have difficulty hearing soft spoken people and young children. They may also have to ask people to speak up or repeat themselves occasionally.|
|Moderate||41 to 55 dB||In addition to missing consonant sounds, vowel sounds then become more difficult to hear. People with a moderate hearing loss often comment that without hearing aids they hear, but can't always understand.|
|Moderately Severe||56 to 70 dB||Without hearing aids, speech becomes inaudible. With hearing aids, speech may still be difficult to understand. You have trouble hearing or understanding everyday conversations or a telephone ringing|
|Severe||71 to 90 dB||Without hearing aids, speech is inaudible, but loud sounds like a baby crying or a dog barking are audible. Hearing aids may no longer be enough for people with severe hearing loss.|
|Profound||91+ dB||Without hearing aids, speech is inaudible, but very loud sounds like a lawn mower or jet airplane are audible. Hearing aids may no longer be enough for people with profound hearing loss and a cochlear implant may be a more effective option|
1. American Speech-Language Hearing Association. Degree of Hearing Loss. Available from http://www.asha.org/public/hearing/Degree-of-Hearing-Loss/. Accessed February 2012
The information on this website is for educational purposes, and is not intended to replace medical advice. Please consult a hearing healthcare professional to diagnose or treat a hearing or health problem.