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Audiogram

You’ve just completed your hearing test. The hearing specialist is now entering the room and provides you with a chart, like the one above, except that it has all of these signs, colors, and lines. This is intended to show you the exact, mathematically precise features 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 focusing on how to improve your hearing. But don’t let it trick you — just because the audiogram looks puzzling doesn’t mean that it’s hard to understand.

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 focus on what really counts: healthier hearing.

Some advice: as you read the article, reference the above blank audiogram. This will make it easier to comprehend, and we’ll address 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 elementary 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 gradually louder sounds until you get to 100 dB.

The horizontal axis records sound frequency, measured in Hertz (Hz). Beginning 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 gradually increase until it reaches 8,000 Hz. Vowel sounds of speech are normally low frequency sounds, while consonant sounds of speech are high frequency sounds.

So, if you were to start at the top left corner of the graph and draw a diagonal line to the bottom right corner, you would be increasing the frequency of sound (shifting from vowel sounds to consonant sounds) while increasing the volume of sound (moving from fainter to louder volume).

Evaluating Hearing and Marking Up the Audiogram

So, what’s with all the markings you usually see on this basic graph?

Simple. Start off at the top left corner of the graph, at the lowest frequency (125 Hz). Your hearing consultant will present you with a sound at this frequency through headphones, beginning with the lowest volume decibel level. If you can perceive 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 again at the next loudest decibel level (10 decibels). If you can perceive it at 10 decibels, a mark is made. If not, continue on to 15 decibels, and so on.

This equivalent technique is reiterated for each frequency as the hearing specialist moves along the horizontal frequency line. A mark is made at the lowest perceivable decibel level you can hear for every sound frequency.

Regarding 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 employed for the right ear. You may discover some other characters, but these are less vital 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 standard 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, locate 25 decibels on the vertical axis, and draw a horizontal line all the way across. Any mark made under this line may display hearing loss. If you can hear all frequencies below this line (25 decibels or higher), then you more than likely have normal hearing.

If, on the other hand, you can’t perceive the sound of a specific frequency at 0-25 dB, you likely have some kind of hearing loss. The lowest decibel level at which you can perceive sound at that frequency establishes the amount of your hearing loss.

As an illustration, 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 lowest 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 connected with normal hearing along with the levels connected 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 signals of hearing loss look like? As many instances of hearing loss are in the higher frequencies (referred to as — you guessed it — high-frequency hearing loss), the audiogram would have a downwards slanting line from the top left corner of the graph sloping 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, since higher-frequency sounds are linked with the consonant sounds of speech, high-frequency hearing loss impairs your ability to comprehend and pay attention to conversations.

There are a few other, less typical patterns of hearing loss that can show up on the audiogram, but that’s probably too much detail for this entry.

Testing Your New Knowledge

You now know the fundamentals of how to interpret an audiogram. So go ahead, arrange that hearing test and impress 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.

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