Hearing Test (Pure Tone Audiogram)

 
The most common type of hearing test is known as Pure Tone Audiometry (PTA). The aim of this test is to establish the quietest sounds you are able to hear at different frequencies or opens a new windowpitches. The test takes around 20 minutes.
 
Procedure:
  • The audiologist will take you into a special soundproof booth or quiet room in which the test will take place.
  • You will have headphones placed over your ears and you will be given a special handset with a response button on it.
  • Your audiologist will play you a series of sounds through these headphones. The sounds will be played into one ear at a time only. The sounds will be simple tones, usually be played at six different pitches that represent the important range of human hearing.
  • Your audiologist will instruct you to press the response button whenever you think that you hear a sound in your headphones, and to hold the button down for as long as you can hear the sound – only letting go of the button when you think the sound has stopped.
  • Each time you correctly hear the sound, the audiologist will reduce the volume slightly, until you are no longer able to hear it. The audiologist will then make a note of the quietest volume at which you were able to hear the sound. 
  • The test will then repeated in your other ear.
 
It is important to follow the instructions carefully. Be sure to ask the audiologist if there is anything you don’t understand, or if you’re not sure what you have to do.
 
 
 An audiologist performing a Pure Tone Audiogram hearing test
You may then be asked to remove the headphones and wear a special vibrating headband that presses on the mastoid bone behind your ear and transfers the sound directly to the inner ear - thereby bypassing the outer and middle ear completely.  This is known as bone conduction and will give the audiologist an indication of whether your hearing loss is of the Conductive or Sensorineural type.
 
 
A patient undergoing a bone conduction hearing test.  Note the vibrating unit positioned on the mastoid bone, behind the ear.
You may also be asked to repeat the test with a constant “rushing” noise playing in your headphones. This is done because, when testing one ear, it is sometimes possible for sounds to be heard by the other ear, via vibrations through the bone of the skull. This process is known as ‘cross hearing’ and can make the hearing (of your poorer ear) seem better than it really is. The purpose of this rushing noise is therefore to ‘mask’ the ear that isn’t being tested, to prevent it hearing the test tones.   
You will actually be instructed to ignore this noise and, as before, asked to respond by pressing the button whenever you hear a test tone. The volume of the rushing noise will vary, but you should always press the button for as long as you think you can hear a tone being played to you, however faint.
Your hearing test results will be recorded on an audiogram chart.
Audiogram Chart
 
The audiogram is a chart that tells clinicians exactly how well you are able to hear tones of different frequencies.
There will be a series of symbols across the chart. The position of these symbols on the chart indicates the quietest sounds you can hear at different frequencies.
The lower down the symbol is on the chart the greater the degree of your hearing loss is at that particular frequency (pitch). Lower pitched sounds are on the left of the chart and higher pitched ones on the right.
PTA Summary
Where is the test done?
GP surgery,
Hospital audiology department
Who carries out the test?
GP
Audiologist
How long does the test take?
20 – 30 minutes
Any discomfort/pain?
None (although concentration is required)
Results ready when?
Instantly
Special equipment used?
Soundproof testing room, headphones, Bone conduction headband, audiometry equipment
Risks/Complications?
None
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