To measure the extent of your hearing loss you may be asked to take a comprehensive hearing test. An audiogram is the result of that test in the form of a graph. The audiometry test is very quick and comfortable. The test measures your ability to hear sounds at various decibel levels and frequencies. On the audiogram graph, the Y or vertical axis represents the intensity of sounds that you were able to hear, measured in decibels (dB), from 0 (the faintest) to 100 (the loudest). On the other horizontal or X axis, you see the frequencies of different sounds, measured in Hertz (Hz); the frequencies range from 100Hz (the lowest bass frequency sounds measured in this test) to 8000Hz (the highest treble frequency sounds measured).
The instrument used to create the audiogram is a device called an audiometer. During the test, the audiologist asks you to wear a pair of padded headphones, and then plays sounds at different frequencies through them, at different volumes. (Note that some of the sounds your brain registers during the hearing test actually arrive there via bone conduction, so you may be asked to where a headband around your forehead that measures this activity.) The test generally starts with the lowest volumes possible. The specialist administering the test will gradually raise the volume until you are first able to hear it.
This process is repeated at additional frequencies. For each frequency tested, the volume at which you are first able to hear it is plotted on a chart – this is the audiogram. Equal hearing across all frequencies appears as a straight horizontal line of dots on the audiogram. But, the lines for real people are rarely straight even if they have perfect hearing. Small variations are normal and expected. When the audiologist sees larger variations, however – not being able to hear sounds in the low frequencies except at high volume, for example – this could demonstrate a type of hearing loss caused by M√©ni√®re’s disease. Alternatively, if you can only hear high-frequency sounds at a high volume, that might be an indicator of a condition called NIHL, or noise-induced hearing loss. If you can’t hear sounds in any frequency except at higher volumes, that may indicate sensorineural hearing loss, such as that caused by otosclerosis.
Whatever the output, the audiogram is an essential tool to determine whether you have experienced hearing loss, and if so, what type of loss it may be, and thus how to treat it most effectively.