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 resulting audiogram, the Y axis (vertical axis) is volume in decibels (db). The testing range is generally 0 to 100 decibels where 0 is very faint and 100 is quite loud. 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 hearing instrument specialist asks you to wear a pair of padded headphones, and then plays sounds at different frequencies through them, at different volumes. You may also be asked to wear a headband that contains an instrument that measures sounds you hear through bone conduction. As you listen, the hearing instrument specialist starts the sounds at their lowest decibel levels, and then slowly raises the volume; when you can hear the sound, you indicate this to the tester.
The specialist will then repeat the process starting with a tone at a new frequency. This produces the audiogram, a series of dots across the graph that represent the volume at which you first were able to hear sounds at different frequencies. 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 hearing instrument specialist 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. Conversely, NIHL (noise-induced hearing loss) is associated with an inability to hear high-frequency sounds at low volumes. If your audiogram shows an inability to hear low volumes across nearly all frequencies, you may have sensorineural hearing loss.
These are just three example of data that your hearing specialist may glean from your audiogram. It is a vital tool in assessing the type of hearing loss you have and the treatments that are most suitable for you.