What is an Audiogram?
Audiologists use a graph called an audiogram to display a person’s level of hearing. It is used to determine what type of hearing loss a person may have and its severity. It specifically measures the softest sound an individual can hear at a wide range of frequencies.
For those who have never seen one, an audiogram can be a little confusing to understand. While it is always best to have an audiologist to help explain, there are three main parts a patient should know.
The x-axis of the graph indicates the frequency of sounds a person can hear and is denoted in Hertz (Hz). A normal hearing audiogram will start around 125 Hz and end at around 8000 Hz. The scale used increases exponentially throughout the test. For example, the frequency denotations go from 125 Hz to 250 Hz, then 500 Hz, 1000 Hz, 2000 Hz, 4000 Hz and finally 8000 Hz.
The lower the number of Hz, the lower the sound. For example, 125 Hz is like a low bass guitar whereas 8000 Hz is more like a bird screeching. Average human voices hit between 120 Hz to 130 Hz, but some can go up to 1000 Hz.
The y-axis of the graph specifies the loudness, or decibels (dB), a person is able to hear. A normal hearing audiogram will have a set range from 10 dB to 120 dB. The threshold of hearing is 0dB, but most audio tests will begin at 10 dB, the sound of humans breathing, and increase by 10dB as the test progresses. Average human voices are around 60 dB and 120 dB can be compared to a loud bar or a shotgun blast.
Your personal results will be shown as two-line graphs, one for each ear, each of which will fall somewhere between the Hertz and Decibel markers indicated above.
Understanding Your Audiogram
An audiogram will have a line graph for both the right and left ear. The right ear is marked with an “O” and the left ear is marked with an “X.” Generally speaking, it is best to have these two lines as close to each other as possible. This means that both ears have similar ranges of hearing. However, there is no need to worry if they are not directly on top of each other.
If both lines are higher up on your audiogram, you have a normal level of hearing.
It is also a good sign if the two lines are both higher up on the audiogram. This indicates a normal level of hearing. The lines might not be straight across because some tones are easier to hear than others. Anywhere from 0 dB to 10 dB across all the frequencies is considered a normal hearing audiogram.
If the test markers are between 10 dB to 40 dB, there is mild hearing loss. This means that it is difficult to hear someone who is speaking softly, sounds coming from a distance, or to locate a specific sound if there is background noise.
If the test markers are between 40 dB to 70 dB, there is moderate hearing loss. People who have moderate hearing loss will have difficulty hearing a typical conversation with a person who is right in front of them. Sounds that are farther off might not even register to them unless it is significantly loud enough.
If the test markers are between 70 dB to 90 dB, there is severe hearing loss. This greatly limits a person. They may only hear emergency sirens or other equally loud sounds. Anything lower and the person might be completely deaf.
What Happens After Testing?
If there are signs of hearing loss, an audiologist will most likely do further testing. Most preliminary tests are done with headphones or speakers, which is called air conduction testing. This test has sound enter through the ear canal, travel past the middle ear, and end up in the inner ear.
If this method shows hearing loss, bone conduction testing may be used. This test uses a bone vibrator to send sound directly into the inner ear by bypassing the ear canal and middle ear where the eardrum is. If hearing levels improve with this test, a person is considered to have conductive hearing loss. If there is no improvement, a person has sensorineural hearing loss.
Depending on the severity of a person’s hearing loss, hearing aids or other supplementary devices may be prescribed.