How to Read an Audiogram
Hearing test result reports are called audiograms. Being able to interpret an audiogram is key to understanding the status of your hearing health. This article is a step-by-step walkthrough of how to read an audiogram, and we share examples of audiograms.
Interpreting What an Audiogram Tells Us
An audiogram is a plot of hearing thresholds across different frequencies. Let us go through the elements one by one to understand how to read an audiogram:
Understanding the Horizontal Axis
The horizontal axis (highlighted below) is the frequencies tested during the hearing test, expressed in terms of Hertz (Hz):
Frequency is sometimes called pitch. As we go from left to right, the frequency increases.
Play the audio clips below to hear what two typical test frequencies sound like:
The subject's sensitivities to sounds at each of the frequencies are tested during a hearing test.
The test might use a pure tone signal similar to the audio clips above. Hearing care professionals have a wide range of test sounds and methods available and use the ones they think are the most suitable for each situation.
In the example above, the test frequencies are 250, 500, 1000, 2000, 4000 and 8000 Hz.
Other, less commonly tested, frequencies are 125, 3000, 6000, 12000 and 16000 Hz.
Understanding the Vertical Axis
The vertical axis (highlighted below) is the hearing thresholds measured during the hearing test, expressed in terms of decibel hearing level (dB HL):
Usually on the left-hand side, numbers (0, 10, ... 120) increase from as you go downward. They indicate the volume or loudness of the sounds required for the subject to hear. The higher the number, the louder the sound. Being able to hear sound from a smaller number represents a better hearing result.
Understanding the Audiogram Symbols
There are international and national standards that specify what an audiogram should look like.
Nevertheless, you may encounter an audiogram which does not conform to expectations.
It is good practice to read the audiogram symbols key (highlighted in the audiogram below) to check what the symbols mean.
According to the legend for this audiogram, left ear thresholds are marked with blue X’s, and right ear thresholds are marked with red O’s.
The table below is an audiogram symbols key, in the format specified by "ISO 8253-1:2010 Acoustics — Audiometric test methods — Part 1: Pure-tone air and bone conduction audiometry":
Tip: You should always read the audiogram symbols key in case you are dealing with an audiogram that does not conform to this standard.
Reading an Audiogram
Consider the audiogram below and try to answer: How would you read the point highlighted by the red arrow?
Our answer is: At 500Hz, the subject had a hearing threshold of 10 dB HL in the right ear, which was within the normal hearing range.
The Four Levels of Hearing Loss
The World Health Organisation (WHO) divides hearing loss into four levels: Mild, moderate, severe and profound hearing loss.
The different degrees of hearing loss are indicated on the audiograms we use in this article.
However, it may not always be available. In that case, you may want to refer to the following table:
|Degree of hearing loss||Hearing threshold (dB HL)|
|Normal hearing||25 dB or lower|
|Mild hearing loss||26 - 40 dB|
|Moderate hearing loss||41 - 60 dB|
|Severe hearing loss||61 - 80 dB|
|Profound hearing loss or deafness||81 dB or higher|
What Does a Hearing Threshold of 0 dB HL Mean?
0 dB HL is a reference value for the average hearing ability of a healthy young adult. The reference levels are defined in international standards.
People with healthy hearing may be able to hear down to 0 dB HL, or even negative dB HL values below zero.
By now, you should understand the basics of how to read an audiogram.
Let us go through some examples of normal audiograms by age and hearing loss types.
Tip: You should compare your hearing ability to normal hearing. Still, it can be interesting to see how we compare to others in our age group.
Normal Hearing Audiogram Example
The following would be considered a normal audiogram:
This test result indicates normal hearing in both ears across all of the frequencies tested.
Next, we will go through some normal hearing test results by age.
Average Audiogram for Those Aged 50-59
While some people develop hearing loss at a young age, the average hearing ability is good until people reach age 50 and above. That is why it is the youngest age group we cover in the examples.
Average Audiogram for Those Aged 60-69
Average Audiogram for Those Aged 70-79
Average Audiogram for Those Aged 80-89
Average Audiogram for Those Aged 90+
Summary: Average Hearing Thresholds In Different Age Groups
We can draw a couple of conclusions from looking at the average hearing thresholds in different age groups:
- We gradually lose our hearing ability when we grow older.
- Our hearing ability typically declines at the higher frequencies first.
Asymmetrical Hearing Loss
Asymmetrical hearing loss is when each ear has a different level or type of hearing loss. Asymmetrical hearing loss is uncommon and signifies that the causes of the losses in each ear are different.
You should visit a hearing care professional if you have an asymmetrical hearing loss to rule out the need for surgery or medical treatment.
An asymmetrical hearing loss could result in an audiogram like this:
Here, the hearing sensitivity in the left ear is significantly weaker than that in the right ear.
Symmetrical Hearing Loss
Symmetrical hearing loss is most natural with age-related hearing loss. It implies that hearing loss is the same in both ears. If both lines or graphs look the same, you have symmetrical hearing loss. The audiogram below reflects symmetrical hearing loss.
Sensorineural Hearing Loss Audiogram
Sensorineural hearing loss is the most common type of hearing loss and is associated with a damaged inner ear or damaged nerves.
The following is a typical sensorineural hearing loss audiogram.
In this audiogram, there are no significant differences between the air-conduction versus bone-conduction hearing thresholds. It suggests the hearing loss was caused by damage to the inner ear or the nerves, which matches the definition of sensorineural hearing loss.
Why the Audiogram is Upside-Down
Usually, the values on a graph are increasing as you go up along the vertical direction.
On audiograms, however, values are increasing in the downward direction instead.
The reasoning behind this convention comes from the basics of what the values on an audiogram represent. An audiogram is a plot of hearing thresholds. A higher threshold means the subject requires louder sounds before they become audible to them. In other words, a higher value represents a worse hearing ability, while lower value represents a better hearing.
The intuitive audiogram interpretation is to see it as a plot of our hearing ability across different frequencies.
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