When you undergo a hearing test, it’s likely that your audiologist or hearing care professional will create an audiogram. An audiogram is a type of chart that is produced when you undergo a hearing test. It is used to evaluate your hearing, providing a visual representation of your current hearing range. Before your next appointment, learn more about what audiograms are, what they show and how to read the results displayed.
An audiogram is created from the results of a test that assesses your hearing threshold levels. During the test, one frequency is played at a time through headphones or earphones, with its volume decreased until it can no longer be heard. The lowest volume that you can hear, measured in decibels, is then identified as your hearing threshold. The process is repeated for several different frequencies and for both ears. The thresholds of each frequency are then plotted across a graph, with a separate line displaying the result of each ear.
Audiograms show your hearing threshold levels, or the softest sound you can detect, at a variety of frequencies. When you undergo a hearing test you’ll be asked whether you can hear certain tones, with the results plotted across the audiogram.
The results displayed by an audiogram can also show whether both ears are affected by hearing loss or if it may be an issue affecting just one. If the results plotted across the chart are quite similar for both ears, it signifies that your hearing is quite even, while asymmetric results could signal a greater hearing deficit in just one ear.
Once the results of the audiogram have been plotted, the shapes of the lines formed may help your audiologist or hearing care professional to identify the type of hearing loss, if any, you are experiencing. If the lines are quite even across all frequencies, this could signal that you have conductive hearing loss, while sloping lines are commonly associated with age-related hearing loss or noise-induced hearing loss.
When you get your hearing checked regularly, audiograms can be useful tools to help your audiologist understand how your hearing may be changing over time. They can be quite easily compared, providing an insight into whether your hearing is worsening or remaining steady. Even if you haven’t noticed any stark changes in your hearing, audiograms may make it easier for changes to be spotted.
Running from the top to the bottom of the audiogram, the vertical axis represents the intensity of the sound and is measured in decibels (dB). A number of different volume levels will be listed along the vertical axis, with the markings made on the audiogram corresponding to the softest level of sound that can be heard for each frequency. The higher the marking is on the audiogram, the better the patient’s hearing is considered to be for that frequency.
The lower thresholds for people within the normal hearing range sit between -10 dB and 25 dB, with higher thresholds generally considered to be an indication of hearing loss. Mild hearing loss falls between 25 dB and 40 dB, moderate hearing loss sits between 40 dB and 55 dB, while moderately severe hearing loss is within the 55 dB to 70 dB range. Severe hearing loss is identified if results sit between 70 dB to 90 dB, and profound hearing loss is identified with readings of 90 dB or higher.
It’s normal to see two different sets of markings on a single audiogram. As each ear is tested separately, the results are then plotted on the graph accordingly, making it easier to tell if the patient is experiencing greater hearing loss in one ear or the other. Different symbols, such as circles and crosses, and different colours, including red and blue, are commonly used.
If you’re unsure of how to read your audiogram, ask your audiologist or hearing care professional to guide you through each of the elements. They’ll be happy to explain what it all means and how the information gathered from your hearing test results will be used.
If a young person with a normal hearing range was to undergo an audiogram test, each of the lines plotted across the chart would sit in the -10 dB to 25 dB range for all frequencies. The lines for each ear would be largely straight, sitting at the top of the chart. As we age, however, our hearing does tend to decline, meaning that the shape of the lines may change over time.