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Audiogram

You have just concluded 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 designed to provide you with the exact, mathematically precise features 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 concentrating on how to improve your hearing. But don’t let it trick you — just because the audiogram looks complex doesn’t mean that it’s difficult to comprehend.

After reading through this article, and with a little terminology and a handful of basic principles, you’ll be reading audiograms like a seasoned 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 comprehend, and we’ll cover all of those cryptic marks the hearing specialist adds later on.

Understanding Sound Frequencies and Decibels

The audiogram is essentially 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 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, faint sound. As you go down the line, the decibel levels increase, representing 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 in general low frequency sounds, while consonant sounds of speech are high frequency sounds.

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

Assessing Hearing and Marking Up the Audiogram

So, what’s with all the marks you usually see on this simple graph?

Easy. Start 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 by means of 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 crossroad of 125 Hz and 0 decibels. If you are not able to perceive the 125 Hz sound at 0 decibels, the sound will be presented again at the next loudest decibel level (10 decibels). If you can hear it at 10 decibels, a mark is made. If not, continue on to 15 decibels, and so on.

This exact method is repeated for every frequency as the hearing specialist proceeds along the horizontal frequency line. A mark is produced at the lowest perceivable decibel level you can hear for every different sound frequency.

Regarding the other symbols? If you observe 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 as a rule applied to mark the points for the left ear; an O is employed for the right ear. You may see some other symbols, but these are less crucial for your basic understanding.

What Normal Hearing Looks Like

So what is considered 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 would this look like on the audiogram?

Just take the empty graph, locate 25 decibels on the vertical axis, and draw a horizontal line completely across. Any mark made under this line may indicate hearing loss. If you can hear all frequencies underneath this line (25 decibels or higher), then you very likely have normal hearing.

If, however, you cannot perceive the sound of a particular frequency at 0-25 dB, you likely have some form of hearing loss. The lowest decibel level at which you can perceive sound at that frequency establishes 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 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 correlated 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? Since the majority of cases 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 chart sloping downward horizontally to the right.

This indicates that at the higher-frequencies, it takes a progressively louder decibel level for you to experience the sound. Furthermore, seeing as higher-frequency sounds are associated with the consonant sounds of speech, high-frequency hearing loss weakens your ability to understand and pay attention to conversations.

There are other, less familiar patterns of hearing loss that can turn up 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, arrange that hearing test and impress your hearing specialist with your newfound talents. 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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