An audiogram is a chart which visually represents someone's hearing. The chart is created by conducting a hearing test in which the softest sounds which someone can hear are noted. When these sounds are plotted, the result is an audiogram. Audiograms can be compared with similar charts from other people to learn more about someone's hearing and determine whether or not it is common for the person's gender, range, and general state of health. They can also be interpreted as standalone documents to identify problematic areas in someone's hearing rage.
The audiogram has two values. Along one axis, usually the horizontal one, the chart is marked with frequencies from low to high. The other axis of the chart documents decibels, starting with zero decibels at the top and moving down to much louder sounds at the bottom. If all of the values on the audiogram fall above the 20 decibel line, it indicates that the subject has normal hearing and can hear sounds within the range of human speech, a zone on the chart known as the "speech banana."
Audiograms have two lines, one for the left ear and one for the right ear. The chart uses different symbols to plot values for different ears. It is important to note that the testing used to generate an audiogram takes place in a highly controlled environment and that someone's actual hearing ability may vary. Audiograms will also not reveal problems with auditory processing. A person with an auditory processing disorder may have a flawless audiogram but still have difficulty understanding spoken language.
One test used to develop an audiogram is a hearing test in which the subject wears headphones and tones are played. The subject signals when he or she can hear a tone and the value is marked down by the test administrator. This test is an air conduction test, meaning that it shows how well sounds are conducted through the air in the ear. In a bone conduction test, a sensor is placed on the mastoid bone to pick up vibrations which move through the ear. Differing results on these tests can provide clues to why someone is experiencing hearing loss.
It is generally recommended that children be screened regularly for hearing loss, along with people in professions which expose them to loud noises, such as construction workers and musicians. For healthy adults, hearing tests should be conducted periodically. Sometimes hearing loss is gradual, and people may not realize that they are having hearing problems.