A hearing test typically consists of several tests to accurately evaluate a person’s hearing ability. All hearing tests include pure tone audiometry, a test that uses generated tones to diagnose hearing impairment.
An audiogram is a chart representing the results of a pure tone audiometry test. A trained audiologist can determine the type and degree of hearing loss from the shape of the audiogram. This article will explain how to read an audiogram and interpret the results.
What Is an Audiogram?
In tone testing, an audiologist plays sounds at various pitches to determine the softest sound a patient can hear at each frequency. This is called the hearing threshold. An audiogram is a graph that the audiologist uses to chart an individual’s hearing thresholds across a range of frequencies.
The tester will check one ear at a time to see if the impairment is greater on the right or left side. The audiologist will also transmit sounds directly into the bone—bone conduction testing— and compare the thresholds to tones sent via the air to check for conductive hearing loss.
This is different from online hearing tests that only test certain tones in your home setting. But they can be an efficient way to see if you would benefit from getting an audiogram test. If you want to try them out, check out our guide on the best online hearing tests.
How to Read an Audiogram
An audiogram is a grid. The horizontal axis represents frequency or pitch, and the vertical axis represents intensity or loudness.
Hearing professionals record the patient’s responses during the audiometry test and interpret the graph to determine the type and degree of hearing loss.
During the hearing test, the audiologist will note the lowest sound level the patient can hear at a given frequency and jot down the hearing threshold on the blank audiogram.
Intensity is used to describe the softest level a patient can hear. It is measured in decibels (dB).
The sound intensity of a face-to-face conversation is around 60 dB, and a whisper is 20 dB. Intensity ranges from -10 dB to 120 dB on an audiogram and is displayed on the y-axis. Hearing thresholds between 0 and 15 dB indicate normal hearing.
Frequency describes the pitch of the sound. It is measured in hertz (Hz).
Humans can detect sounds of frequencies 20 to 20,000 Hz.
For example, waves and thunder are low-frequency sounds, whereas whistles and sounds of birds chirping are high-frequency sounds.
Did you know there are also word recognition tests, used for evaluating your capacity to understand speech without any visual cues? Read more about them in our guide.
Audiogram Symbols and Their Meaning
Audiologists use a standard set of audiometric symbols to record the patient’s hearing thresholds. In order to read an audiogram, you need to understand what the symbols represent.
- A circle or a triangle represents hearing thresholds of the right ear measured using headphones. These are typically red.
- An “X” or a square represents the hearing thresholds of the left ear measured using headphones. These are typically blue.
- An “S” represents hearing thresholds measured using a speaker.
- A “<” or “[“ represents bone conduction thresholds of the right ear.
- A “>” or “]” represents bone conduction thresholds of the left ear.
Normal Hearing on Audiogram
Hearing thresholds between -10 dB to 15 dB indicate normal hearing sensitivity. You have normal hearing ability if you can hear sounds at 15 dB or less across the testing range.
Degrees of Hearing Loss
After viewing the audiogram results, the audiologist will classify your hearing ability based on hearing thresholds. There are six degrees of hearing loss.
Degree of hearing loss
0 – 15
Slight Hearing Loss
16 – 25
Mild Hearing Loss
26 – 40
Moderate Hearing Loss
41 – 55
Moderately Severe Hearing Loss
56 – 70
Severe Hearing Loss
71 – 90
Profound Hearing Loss
Note: The pure tone average (average of hearing thresholds obtained at 500, 1000, and 2000 Hz) is typically used to calculate the severity of hearing loss.
Types of Hearing Loss
Hearing loss is categorized according to where the impairment occurs.
Conductive Hearing Loss
Conductive hearing loss occurs when the sound signals are not effectively transmitted from the outer or middle ear to the inner ear. Common causes include:
- Fluid buildup in the ear
- Hole or tear in the eardrum
- Earwax impaction in the ear canal
- Middle ear disorders
Conductive loss is often reversible through surgery, earwax removal, or other medical treatments.
Sensorineural Hearing Loss
Sensorineural hearing impairment is caused by damage to the inner ear or auditory nerve. It is usually irreversible. Age-related and noise-induced hearing loss are the two most common forms of sensorineural hearing disorders. Other causes include:
- Toxic reactions to medications
- Neurological disorders
- Head trauma
- Congenital disorders
The most common treatment options are hearing aids or cochlear implants.
Mixed hearing loss
When a person shows both of the above-mentioned hearing disorders simultaneously, their hearing loss is considered “mixed.” The conductive and sensorineural components are treated separately. This usually means a combination of medical or surgical treatment and hearing aids.
Examples of Audiogram Results
Below are a few examples of audiograms corresponding to normal hearing, conductive hearing loss, and sensorineural hearing loss.
In this audiogram, the air conduction thresholds of both the right and left ear are below 15 dB. This means the individual has normal hearing sensitivity and can detect sound levels of 15 dB or below.
Conductive Hearing Loss
A significant difference between the results of air conduction and bone conduction testing signifies conductive hearing loss. People with normal hearing should hear sounds through the air better, but the lines should be relatively similar.
In the above audiogram, the bone conduction thresholds (denoted by “>”) are within the normal limits (below 15 dB). The air conduction thresholds (indicated by “X”) fall under 45 dB to 60 dB. This means that the incoming sound signals are disrupted somewhere in the air conduction pathway.
Sensorineural Hearing Loss
The above chart represents the hearing thresholds of a person with sensorineural hearing loss. The air and bone conduction thresholds are at similar levels, but there is more significant loss in the highest frequencies. When people have damage or degradation in the inner ear, they typically lose their ability to hear higher frequencies first.
What Happens After Audiometry Test
After the test, the audiologist will study the audiogram and determine the type and degree of hearing loss. The professional will then recommend treatment options based on your hearing ability.
Hearing aids are the most common treatment option for moderate or mild hearing loss.
However, people with severe or profound hearing loss may consider cochlear implants. If the audiologist believes the cause is reversible, they may refer you to an ENT for surgical or medical treatments.
Audiograms provide valuable information to a hearing care professional on the type and extent of a patient’s hearing loss. The audiologist will also use these results during hearing aid programming to set the minimum and maximum sound amplification provided by the hearing aids.
If you have difficulty hearing a normal conversation, you might be hard of hearing. Contact an audiologist today to set up an exam.