How to Read Your Audiogram at Your Hearing Test
You’ve just concluded your hearing test. The hearing specialist is now coming into the room and presents you with a graph, like the one above, except that it has all of these icons, colors, and lines. This is intended to explain to 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 complexity at a time when you’re supposed to be focusing on how to strengthen your hearing. But don’t let it fool you — just because the audiogram looks perplexing doesn’t mean that it’s difficult to grasp.
After going over this article, and with a little terminology and a few basic concepts, you’ll be reading audiograms like a seasoned professional, so that you can concentrate on what actually counts: better hearing.
Some advice: as you read the article, reference the above blank audiogram. This will make it much easier to understand, and we’ll tackle all of those cryptic marks the hearing specialist adds later.
Understanding Sound Frequencies and Decibels
The audiogram is really just a chart 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 basic 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, standing for gradually 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 continue along the horizontal axis to the right, the frequency will steadily increase until it reaches 8,000 Hz. Vowel sounds of speech are generally low frequency sounds, while consonant sounds of speech are high frequency sounds.
And so, if you were to start off 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 increasing the intensity of sound (moving from fainter to louder volume).
Assessing Hearing and Marking Up the Audiogram
So, what’s with all the marks you normally see on this simple graph?
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 earphones, beginning with the smallest volume decibel level. If you can hear it at the lowest level (0 decibels), a mark is made at the convergence of 125 Hz and 0 decibels. If you can’t 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 hear it at 10 decibels, a mark is made. If not, advance on to 15 decibels, and so on.
This same method is reiterated for each frequency as the hearing specialist proceeds along the horizontal frequency axis. A mark is created at the lowest perceivable decibel level you can hear for every sound frequency.
As for the other symbols? If you see 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 generally applied to mark the points for the left ear; an O is applied for the right ear. You may notice some additional symbols, but these are less important for your basic understanding.
What Normal Hearing Looks Like
So what is thought to be normal hearing, and what would that look like on the audiogram?
Individuals with regular 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 completely across. Any mark made under this line may suggest hearing loss. If you can hear all frequencies below this line (25 decibels or higher), then you more than likely have normal hearing.
If, however, you cannot perceive the sound of a specified frequency at 0-25 dB, you probably have some type of hearing loss. The lowest decibel level at which you can perceive sound at that frequency pinpoints the grade of your hearing loss.
As an illustration, consider the 1,000 Hertz frequency. If you can perceive this frequency at 0-25 decibels, you have normal hearing for this frequency. If the smallest decibel level at which you can perceive this frequency is 40 decibels, for example, then you have moderate hearing loss at this frequency.
As a summary, here are the decibel levels associated with normal hearing along with the levels correlated 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 might an audiogram with marks of hearing loss look like? Seeing as 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 descending sloping line from the top left corner of the chart sloping downward horizontally to the right.
This means that at the higher-frequencies, it takes a progressively louder decibel level for you to perceive the sound. Furthermore, since 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 other, less typical patterns of hearing loss that can turn up on the audiogram, but that’s probably too much information for this entry.
Testing 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 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.