You have just finished your hearing test. The hearing specialist is now entering the room and presents you with a graph, like the one above, except that it has all of these characters, colors, and lines. This is designed to highlight to you the exact, mathematically precise attributes of your hearing loss, but to you it may as well be written in Greek.
The audiogram adds confusion and complexity at a time when you’re supposed to be directing your focus on how to enhance your hearing. But don’t let it trick you — just because the audiogram looks puzzling doesn’t mean that it’s hard to interpret.
After looking through this article, and with a little terminology and a few basic principles, you’ll be reading audiograms like a pro, so that you can focus on what actually counts: healthier hearing.
Some advice: as you read the article, reference the above blank audiogram. This will make it much easier to comprehend, and we’ll address all of those cryptic marks the hearing specialist adds later on.
Understanding Sound Frequencies and Decibels
The audiogram is basically just a graph that records sound volume on the vertical axis and sound frequency on the horizontal axis. (are you having flashbacks to high school geometry class yet?) Yes, there’s more to it, but at a elementary level it’s just a chart graphing two variables, as follows:
The vertical axis records sound intensity or volume, measured in decibels (dB). As you move up the axis, the sound volume decreases. So the top line, at 0 decibels, is a very soft, faint sound. As you move down the line, the decibel levels increase, representing progressively louder sounds until you get to 100 dB.
The horizontal axis records sound frequency, measured in Hertz (Hz). Starting at the top left of the graph, you will see a low frequency of 125 or 250 Hz. As you keep moving along the horizontal axis to the right, the frequency will gradually increase until it arrives at 8,000 Hz. Vowel sounds of speech are commonly low frequency sounds, while consonant sounds of speech are high frequency sounds.
And so, if you were to begin at the top left corner of the graph and sketch a diagonal line to the bottom right corner, you would be raising the frequency of sound (going from vowel sounds to consonant sounds) while raising the intensity of sound (moving from softer to louder volume).
Testing Hearing and Marking Up the Audiogram
So, what’s with all the marks you usually see on this basic chart?
Easy. Start at the top left corner of the graph, at the lowest frequency (125 Hz). Your hearing specialist will present you with a sound at this frequency through headsets, starting with the lowest volume decibel level. If you can hear it at the lowest level (0 decibels), a mark is created at the intersection point of 125 Hz and 0 decibels. If you are not able to hear the 125 Hz sound at 0 decibels, the sound will be provided once more at the next loudest decibel level (10 decibels). If you can perceive it at 10 decibels, a mark is made. If not, proceed on to 15 decibels, and so on.
This identical method is duplicated for every frequency as the hearing specialist moves along the horizontal frequency line. A mark is made at the lowest perceivable decibel level you can perceive for each individual sound frequency.
In terms of the other symbols? If you notice two lines, one is for the left ear (the blue line) and one is for the right ear (the red line: red is for right). An X is most often used to mark the points for the left ear; an O is employed for the right ear. You may discover some other symbols, but these are less important for your basic understanding.
What Normal Hearing Looks Like
So what is judged as normal hearing, and what would that look like on the audiogram?
People with normal hearing should be able to perceive every sound frequency level (125 to 8000 Hz) at 0-25 decibels. What might this look like on the audiogram?
Take the blank graph, locate 25 decibels on the vertical axis, and draw a horizontal line all the way across. Any mark made underneath this line may display hearing loss. If you can perceive all frequencies below this line (25 decibels or higher), then you most likely have normal hearing.
If, on the other hand, you cannot perceive the sound of a specified frequency at 0-25 dB, you probably have some form of hearing loss. The lowest decibel level at which you can perceive sound at that frequency determines the extent of your hearing loss.
For instance, take the 1,000 Hertz frequency. If you can perceive this frequency at 0-25 decibels, you have normal hearing for this frequency. If the minimum decibel level at which you can hear this frequency is 40 decibels, for instance, then you have moderate hearing loss at this frequency.
As an overview, here are the decibel levels correlated with normal hearing along with the levels associated with mild, moderate, severe, and profound hearing loss:
Normal hearing: 0-25 dB
Mild hearing loss: 20-40 dB
Moderate hearing loss: 40-70 dB
Severe hearing loss: 70-90 dB
Profound hearing loss: 90+ dB
What Hearing Loss Looks Like
So what would an audiogram with evidence of hearing loss look like? Since the majority of cases of hearing loss are in the higher frequencies (referred to as — you guessed it — high-frequency hearing loss), the audiogram would have a downward slanting line from the top left corner of the graph sloping downward horizontally to the right.
This will mean that at the higher-frequencies, it requires a progressively louder decibel level for you to experience the sound. Furthermore, considering that higher-frequency sounds are connected with the consonant sounds of speech, high-frequency hearing loss weakens your ability to comprehend and pay attention to conversations.
There are some other, less prevalent patterns of hearing loss that can show up on the audiogram, but that’s probably too much information for this article.
Testing Your New Knowledge
You now know the nuts and bolts of how to read an audiogram. So go ahead, book that hearing test and impress your hearing specialist with your newfound abilities. And just imagine the look on their face when you tell them all about your high frequency hearing loss before they even say a word.