An audiogram is the output – in the form of a graph – of a test that our specialists at Audiology and Hearing Aid Services can perform to test the state of your hearing, and to help determine whether you have suffered any hearing loss. The test is painless, and can be completed in only a few minutes. 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). The X or horizontal axis represents the frequency of the sound in Hertz (Hz), on a scale from 100Hz (the lowest frequency sounds tested, equivalent to low bass notes in the second octave of a piano) to 8000Hz (the highest frequency sounds tested, equivalent to the highest notes of bird songs).
The graph is created by a testing device called an audiometer. When audiologists give you a hearing test using this equipment, they ask you to put on a pair of foam-padded headphones, through which sounds are played at different frequencies and at different volumes. You may also be asked to wear a headband that contains an instrument that measures sounds you hear through bone conduction. During the test, sounds are played at their lowest possible decibel levels, and then the volume is slowly raised, and you indicate to the audiologist when you can first hear them.
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. Ideally, the line represented by the different dots would be straight, indicating equal hearing ability at all frequencies, but in practice everyone’s audiogram will be slightly different, even if they have perfect hearing. Large differences, however – an inability to hear faint sounds in the low frequencies, for example – might be an indicator of a particular type of hearing loss, in this case one commonly caused by Ménière’s disease.An inability to hear low-volume high-frequency sounds could indicate a type of hearing loss caused by exposure to loud sounds, called noise-induced hearing loss (NIHL). A significant inability to hear low volumes at all frequencies might indicate otosclerosis, a common form of sensorineural hearing loss.
Whatever the output, it will help the specialists at Audiology and Hearing Aid Services 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.