Hearing Losses and Audiograms
Audiograms
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An audiogram is a visual representation of your child’s hearing. The intensity of sound is shown up and down the vertical axis of the audiogram. Intensity relates to loudness, which is measured in decibels (dB). The farther down the audiogram, the louder something is. Frequency of sound is measured along the horizontal axis. Frequency relates to pitch, which is measured in Hertz (Hz). Frequency is how many sound waves are traveling per second, the faster the waves, the higher the sound. The highest sounds are in the top right corner of the audiogram.
What is Normal?
This audiogram shows a normal hearing range, which ranges from -10-20 dBHL. This picture also shows the “speech banana.” This yellow “banana” shows the location of speech sounds on an audiogram.
An audiogram is able to show the degree of hearing loss in both ears. There are two different hearing tests that may be used: air conduction and bone conduction. An air conduction test sends sound all the way through the ear, while a bone conduction test only sends it to the brain. Each test has its own pictorial representation on the audiogram.
What is Normal?
This audiogram shows a normal hearing range, which ranges from -10-20 dBHL. This picture also shows the “speech banana.” This yellow “banana” shows the location of speech sounds on an audiogram.
An audiogram is able to show the degree of hearing loss in both ears. There are two different hearing tests that may be used: air conduction and bone conduction. An air conduction test sends sound all the way through the ear, while a bone conduction test only sends it to the brain. Each test has its own pictorial representation on the audiogram.
Legend of Audiogram Symbols
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Hearing Ranges
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Conductive Hearing Loss
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A conductive loss is defined as having a dysfunctional outer or middle ear with a normally functioning inner ear. This is not a problem of sound perception (a brain job), but a problem of sound conduction (an ear job). Wax or objects blocking the external auditory canal can cause this. A conductive loss may also be caused by otitis media, fluid in the middle ear or otosclerosis.
In this audiogram, the bone conduction test (>) shows that sound is reaching the brain fine. However, the air conduction test is saying there is a moderate loss. This means something in the outer or middle ear is hindering sound from reaching the brain.
In this audiogram, the bone conduction test (>) shows that sound is reaching the brain fine. However, the air conduction test is saying there is a moderate loss. This means something in the outer or middle ear is hindering sound from reaching the brain.
Sensorineural Hearing Loss
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A sensorineural loss is defined as having a dysfunctional inner ear with a normally functioning outer and middle ear. This is a problem of sound perception, not sound conduction. Some of the causes of a sensorineural loss are premature birth, cytomegalovirus (CMV) and meningitis.
This audiogram of a sensorineural loss shows the bone conduction and air conduction tests lining up. These results show there is a problem of sound perception, rather than conduction. The sound may be traveling fine through the outer and middle ear, but is getting trapped in the inner ear.
This audiogram of a sensorineural loss shows the bone conduction and air conduction tests lining up. These results show there is a problem of sound perception, rather than conduction. The sound may be traveling fine through the outer and middle ear, but is getting trapped in the inner ear.
Mixed Hearing Loss
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A mixed loss is a hearing loss that occurs in both the inner ear and either one or both of the outer and middle ear. This will be seen on an audiogram with both air and bone conduction tests showing a loss. However, the lines will most likely not be lying on top of one another. The tests will be showing different levels of hearing loss. This will show that there is a problem of sound conduction and sound perception.
References:
Austin, Ellen. “The World of Deafness: Teaching Deaf and Hard of Hearing Students.” Powerpoint. Radford University. 2 Dec. 2012.
Austin, Ellen. “The World of Deafness: Teaching Deaf and Hard of Hearing Students.” Powerpoint. Radford University. 2 Dec. 2012.