You have just finalized your hearing test. The hearing specialist is now coming into 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 supposed 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 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 deceive you — just because the audiogram looks complicated doesn’t mean that it’s hard to understand.
After looking through this article, and with a little terminology and a few basic concepts, you’ll be reading audiograms like a professional, so that you can concentrate on what really matters: better hearing.
Some advice: as you read the article, reference the above blank audiogram. This will make it easier to understand, and we’ll cover all of those cryptic marks the hearing specialist adds later on.
Understanding Sound Frequencies and Decibels
The audiogram is basically just a diagram 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 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, weak sound. As you go down the line, the decibel levels increase, representing steadily 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 along the horizontal axis to the right, the frequency will progressively increase until it gets to 8,000 Hz. Vowel sounds of speech are in general 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 raising the frequency of sound (shifting from vowel sounds to consonant sounds) while increasing the volume of sound (moving from softer to louder volume).
Assessing Hearing and Marking Up the Audiogram
So, what’s with all the marks you normally see on this basic graph?
Simple. Start at the top left corner of the graph, at the lowest frequency (125 Hz). Your hearing professional will present you with a sound at this frequency by way of headsets, beginning with the smallest volume decibel level. If you can perceive it at the lowest level (0 decibels), a mark is created at the convergence of 125 Hz and 0 decibels. If you are not able to hear the 125 Hz sound at 0 decibels, the sound will be presented once more at the next loudest decibel level (10 decibels). If you can perceive it at 10 decibels, a mark is created. If not, advance on to 15 decibels, and so on.
This same routine is carried out for every frequency as the hearing specialist travels along the horizontal frequency axis. A mark is created at the lowest perceivable decibel level you can hear for every different sound frequency.
Regarding 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 normally applied to mark the points for the left ear; an O is employed for the right ear. You may see some additional characters, but these are less relevant for your basic understanding.
What Normal Hearing Looks Like
So what is considered to be 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 might this look like on the audiogram?
Just take the blank graph, locate 25 decibels on the vertical axis, and draw a horizontal line entirely across. Any mark made beneath 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 can’t perceive the sound of a specific frequency at 0-25 dB, you very likely have some kind of hearing loss. The lowest decibel level at which you can perceive sound at that frequency pinpoints the degree of your hearing loss.
As an example, 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 lowest decibel level at which you can perceive 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 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 indications of hearing loss look like? Because many cases of hearing loss are in the higher frequencies (labeled as — you guessed it — high-frequency hearing loss), the audiogram would have a downwards sloping line from the top left corner of the chart slanting downward horizontally to the right.
This means that at the higher-frequencies, it takes 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 a few other, less common patterns of hearing loss that can appear on the audiogram, but that’s probably too much information for this article.
Testing Your New Knowledge
You now know the basics of how to read an audiogram. So go ahead, book that hearing test and surprise your hearing specialist with your newfound talents. 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.