You’ve just concluded your hearing test. The hearing specialist is now entering the room and presents you with a chart, like the one above, except that it has all of these icons, colors, and lines. This is intended to show you the exact, mathematically precise attributes of your hearing loss, but to you it might as well be written in Greek.
The audiogram creates confusion and complication at a time when you’re supposed to be concentrating on how to strengthen your hearing. But don’t let it deceive you — just because the audiogram looks perplexing doesn’t mean that it’s difficult to comprehend.
After reading through this article, and with a little vocabulary and a handful of basic principles, you’ll be reading audiograms like a professional, so that you can concentrate on what really 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 markings the hearing specialist adds later on.
Understanding Sound Frequencies and Decibels
The audiogram is really 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 fundamental level it’s just a chart graphing two variables, as follows:
The vertical axis documents 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 increasingly 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 move over along the horizontal axis to the right, the frequency will progressively increase until it gets to 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 increasing the frequency of sound (progressing from vowel sounds to consonant sounds) while raising the intensity of sound (moving from softer to louder volume).
Assessing Hearing and Marking Up the Audiogram
So, what’s with all the markings you usually see on this simple chart?
Easy. Begin 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 by means of earphones, starting with the lowest volume decibel level. If you can perceive it at the lowest level (0 decibels), a mark is created at the crossroad of 125 Hz and 0 decibels. If you can’t perceive the 125 Hz sound at 0 decibels, the sound will be provided again at the next loudest decibel level (10 decibels). If you can hear it at 10 decibels, a mark is created. If not, continue on to 15 decibels, and so on.
This identical method is carried out for each frequency as the hearing specialist moves along the horizontal frequency axis. A mark is created at the lowest perceivable decibel level you can hear 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 typically used to mark the points for the left ear; an O is used for the right ear. You may notice some additional characters, but these are less significant for your basic understanding.
What Normal Hearing Looks Like
So what is deemed as normal hearing, and what would that look like on the audiogram?
Individuals with regular hearing should be able to perceive each sound frequency level (125 to 8000 Hz) at 0-25 decibels. What would this look like on the audiogram?
Take the blank graph, find 25 decibels on the vertical axis, and draw a horizontal line completely across. Any mark made underneath this line may suggest hearing loss. If you can hear all frequencies beneath this line (25 decibels or higher), then you most likely have normal hearing.
If, however, you cannot perceive the sound of a certain frequency at 0-25 dB, you probably have some kind of hearing loss. The smallest decibel level at which you can perceive sound at that frequency establishes the amount of your hearing loss.
For instance, consider the 1,000 Hertz frequency. If you can hear 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 a summary, here are the decibel levels identified 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 signs of hearing loss look like? Considering that many instances of hearing loss are in the higher frequencies (labeled as — you guessed it — high-frequency hearing loss), the audiogram would have a downward sloping line from the top left corner of the graph slanting downward horizontally to the right.
This means that at the higher-frequencies, it requires a increasingly louder decibel level for you to experience the sound. And, considering that higher-frequency sounds are linked with the consonant sounds of speech, high-frequency hearing loss damages your ability to understand and pay attention to conversations.
There are a few other, less typical patterns of hearing loss that can appear on the audiogram, but that’s probably too much detail for this entry.
Test Your New-Found Knowledge
You now know the nuts and bolts of how to read an audiogram. So go ahead, schedule that hearing test and surprise your hearing specialist with your newfound abilities. And just think about the look on their face when you tell them all about your high frequency hearing loss before they even say a word.