You’ve just concluded your hearing test. The hearing specialist is now entering the room and provides you with a graph, like the one above, except that it has all of these icons, colors, and lines. This is designed to provide you with the exact, mathematically precise attributes of your hearing loss, but to you it may as well be written in Greek.
The audiogram contributes confusion and complication at a time when you’re supposed to be focusing 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 comprehend.
After reading this article, and with a little terminology and a few basic principles, you’ll be reading audiograms like a professional, so that you can focus on what really counts: better hearing.
Some advice: as you read the article, reference the above blank audiogram. This will make it much easier to comprehend, and we’ll cover all of those cryptic markings the hearing specialist adds later on.
Understanding Sound Frequencies and Decibels
The audiogram is essentially 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 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 go down the line, the decibel levels increase, standing for 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 continue along the horizontal axis to the right, the frequency will gradually increase until it gets to 8,000 Hz. Vowel sounds of speech are usually 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 (progressing from vowel sounds to consonant sounds) while raising the strength of sound (moving from softer to louder volume).
Examining Hearing and Marking Up the Audiogram
So, what’s with all the marks you normally see on this simple chart?
Simple. 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 through 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 junction of 125 Hz and 0 decibels. If you can’t perceive 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 same method is reiterated for every frequency as the hearing specialist progresses along the horizontal frequency line. A mark is created at the lowest perceivable decibel level you can perceive 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 typically used to mark the points for the left ear; an O is applied for the right ear. You may see some other symbols, but these are less vital 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?
People with normal hearing should be able to perceive every sound frequency level (125 to 8000 Hz) at 0-25 decibels. What would this look like on the audiogram?
Just take the empty graph, find 25 decibels on the vertical axis, and draw a horizontal line completely across. Any mark made below this line may indicate hearing loss. If you can hear all frequencies beneath this line (25 decibels or higher), then you 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 type of hearing loss. The lowest decibel level at which you can perceive sound at that frequency establishes the stage of your hearing loss.
For 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 smallest 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 associated 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 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 downward slanting line from the top left corner of the chart sloping downward horizontally to the right.
This signifies that at the higher-frequencies, it requires a increasingly louder decibel level for you to experience the sound. Furthermore, considering that higher-frequency sounds are associated with the consonant sounds of speech, high-frequency hearing loss impairs your ability to comprehend and follow conversations.
There are a few other, less typical patterns of hearing loss that can appear on the audiogram, but that’s probably too much information for this entry.
Test Your New-Found Knowledge
You now know the fundamentals of how to read an audiogram. So go ahead, arrange 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.