Chances are you’ve recently been to an Audiologist, and they have performed an audiometry test. Now you would like to understand what the Audiogram chart means.
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 word recognition tests are also used to evaluate your capacity to understand speech without any visual cues? Read more about them in our guide.
Audiogram Symbols and Their Meaning
- A circle or a triangle represents the 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 average 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 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 inner ear or auditory nerve damage. It is usually irreversible. Age-related and noise-induced hearing loss are the two most common 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 hearing mentioned above disorders simultaneously, their hearing loss is considered “mixed.” This usually means a combination of medical or surgical treatment and hearing aids. The conductive and sensorineural components are treated separately.
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 right and left ear air conduction thresholds 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 air conduction and bone conduction testing results 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 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 a 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 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.