The ABCs of audiograms
Admitting you have hearing loss is a big step. Whether you came to that realization on your own or whether your family pleaded, cajoled and begged, the result is the same: you are finally going to meet with a hearing care professional for a hearing test. The appointment has been on the calendar for a couple of weeks, and now the big day is finally here. With apprehension you get in the car to drive to the appointment, unsure of what to expect.
The good news is that the testing isn’t painful, and is over relatively quickly. Before you leave you will be presented with a graph, called an audiogram, which looks suspiciously like something you remember from your junior high math class. To you, it might look like a bunch of indecipherable lines and symbols, or something you might see illustrating the NASDAQ report on the nightly news. But once you learn how to read an audiogram, you can better understand your hearing loss. Even more important, your hearing care professional will use the results to determine the type of hearing aid that could most benefit you.
How to read an audiogram
Knowledge is power, especially when it comes to hearing aid advocacy. So today we’re going back to school to show you how to read your audiogram, in order for you to have a thorough understanding of your hearing loss.
The goal of audiometric testing, or hearing testing, is to measure your hearing ability across a range of frequencies in each ear independently. This testing produces the chart called an audiogram. The audiogram charts your hearing ability, or the softest sounds you are able to hear at various frequencies. It asks one basic question: What are the softest sounds a person can hear at each frequency 50 percent of the time?
An important thing to remember is that the audiogram is quantitative, not qualitative. That is to say it uses a specific numerical system to accurately measure how much hearing you have and at what frequency that hearing occurs, instead of subjectively describing the quality of your hearing.
Looking at the audiogram, you will see two axes. The horizontal axis represents frequency (lowest to highest). The lowest frequency represented is between 125 and 250 Hertz (Hz), and the highest is about 8000 Hz. To put it in perspective, think of the frequency axis like the keys on a piano where the sounds become higher pitched as you progress from left to right. Most speech falls into the 250 to 6000 Hz range, with the vowel sounds among the lowest frequencies and the consonants such as S, F, SH, CH, H, TH, T, K and soft C sounds among the highest frequencies.
The vertical axis of the audiogram represents decibel level (loudness or intensity of sound). It is important to note that although the top left of the chart is labeled 0 decibels, that does not mean the absence of sound entirely. Zero decibels actually represents the lowest level of sound that a normal human ear is able to detect. For a person with normal hearing ability, the threshold, or the softest sounds a person can hear, is anywhere from 0 to 15 decibels in children and anywhere from 0 to 25 decibels in adults.
The symbols on an audiogram
Now, reading the graph requires some explanation of the symbols. Remember the left ear is represented in blue, and the right ear is represented in red. Ideally the responses from each ear are plotted on the same audiogram, but sometimes they are plotted on two separate audiograms.
Each symbol on the chart represents the lowest decibel level you can hear at a particular frequency. For example, a person might not be able to hear a 3000-Hz sound if the decibel level is below 40. That point would then be plotted on the graph. Once all of the points are plotted, they are connected to form easy-to-read lines for the left and right ears.
Here it should be mentioned that if the two lines are essentially overlapping, your hearing loss is considered symmetrical, or the same in both ears. If the lines are not overlapping your hearing loss is considered asymmetrical, meaning your ears have differing degrees of hearing loss.
Which symbols you see are dependent on the type of hearing test conducted. Testing with headphones is called air conduction because the sound must travel through the air of the ear canal to reach the inner ear. The air conduction results for the right ear are marked with a red “O," and the results for the left ear are marked with a blue “X." Bone conduction testing, in which a device is placed behind the ear in order to transmit sound through vibration of the mastoid bone, is marked with a “[“or a “<” symbol. These symbols are often displayed in red or blue for the right or left ear, respectively.
What is normal hearing?
Looking at your audiogram, now highlight the 25 dB line that crosses the graph from left to right. If your Xs and Os fall above the highlighted line, your hearing ability is considered within normal limits. Any Xs or Os below that highlighted line, however, indicates a hearing loss.
So how bad is it? Your hearing care professional will classify the severity of your hearing loss by how far down the graph the marks go, and in what frequencies the loss occurs. Hearing loss can range from mild to profound.
Keep a copy of your audiogram
Afterward, it is important that you request a copy of your test results. Not only will these results serve as a prescription for you, but it will serve as a baseline for you and your hearing care professional to monitor any changes in your hearing down the road.
If you have been struggling to hear or have noticed a feeling of fullness in your ears, making an appointment with a hearing care professional is the first step. But it doesn’t end there; knowing how to read your own audiogram allows you to be an active participant in your hearing healthcare treatment and to make the most informed decisions when it comes to your hearing aids.