How to interpret an audiogram

Reading Time: 10 minutes
Written by Amplivox
14/05/2024

An audiogram is the main output of a hearing test. Audiologists commonly use this type of test output to document and analyse their patient's hearing threshold across different frequencies.

Audiologists record audiogram results using pure-tone audiometry, which is the gold standard for understanding type, level, and pattern of hearing loss. Pure-tone audiometry is widely available, very dependable, and simple to perform.

Audiogram interpretation is crucial for an audiologist to be able to recommend appropriate hearing loss interventions. The results provide a basis for diagnosis, reassurance, monitoring, or further investigation of any ear concerns. Some options for treating hearing loss include hearing aids, cochlear implants, and surgery.

There are three types of hearing loss:

  • Conductive hearing loss: is hearing loss in the external ear or middle ear
  • Sensorineural hearing loss: is inner ear hearing loss
  • Mixed hearing loss: is when conductive and sensorineural hearing loss occur together

 

audiogram

Figure 1. Example of an audiogram

 

The horizontal axis (x-axis) 

This represents frequency (pitch) from lowest to highest (left to right). The lowest frequency tested is usually 125Hz, and the highest frequency is usually 8000Hz.

We test these frequencies because most speech falls into the 250 to 6000 Hz range. Vowel sounds are among the lowest frequencies and consonants such as S, F, SH, CH, H, TH, T and K sounds are among the higher frequencies.

The vertical axis (y-axis)

The y-axis of the audiogram shows the intensity (loudness) of sound, measured in decibels (dB HL). The graph shows the lowest or softest sound levels at the top and the loudest or highest at the bottom.

 

Audiograms use symbols to show how well someone can hear at different volumes during testing. Audiologists conduct audiology tests through air and bone conduction which use different symbols.

Air conduction

Testing with headphones is known as air conduction (AC) testing. This is because the sound travels through the air in the ear canal to reach the inner ear.

  • A red "O" marks the air conduction results for the right ear
  • A blue "X" marks the air conduction results for the left ear


Bone conduction

Bone conduction testing uses a device (bone oscillator) behind the ear to transmit sound through the mastoid bone. It's marked with a “>“ or a “<” symbol. Depending on the region this symbol can differ.

Each symbol on the graph represents the bone conduction threshold for a given frequency. When all the thresholds are measured and plotted on the graph, they're connected to form easy-to-read lines. This is done for both the left and right ears.

If the two lines overlap, we consider the hearing loss symmetrical - meaning it's essentially the same in both ears. If the lines don't overlap, hearing loss is considered to be asymmetrical, i.e., each ear has a different level of hearing loss. Hearing loss should occur equally in both ears.

 

Figure 2. Hearing loss categorisation

A hearing specialist can determine how severe the hearing loss is by reviewing where the symbols are on the graph. There are many potential levels of hearing loss:

 

Mild hearing loss Moderate hearing loss
Refers to thresholds ranging between 26–40 decibels. A person might be do well in face-to-face conversations, but struggle with hearing distant noises or quiet voices. They might also find it difficult to communicate in noisy environments. Refers to thresholds ranging between 45–65 decibels. Someone might have trouble hearing in any situation and find it especially hard to hear in loud places. 
Severe hearing loss   Profound hearing loss
Refers to thresholds that range between 66–85 decibels. A person can only hear someone if they speak loudly in a very quiet environment.  Refers to thresholds greater than 85 decibels. If a person has profound hearing loss, they might only be able to hear incredibly loud sounds. They'll struggling with hearing and understanding speech, even when the environment is extremely quiet. 

 

It's important to have routine hearing tests to identify any signs of hearing loss at an early stage. Hearing tests can be done in the community, at work, or by visiting a doctor or audiologist. 

At Amplivox, we've developed a suite of innovative and user-friendly diagnostic audiometers to suit a whole range of hearing loss pathologies. 

The Model 270+ is an advanced two-channel diagnostic audiometer used by audiologists, ENTs, and hearing aid suppliers. The device includes manual and automatic testing for bone conduction, as well as air conduction (Hughson Westlake and Békésy). Along with intuitive tools that help hearing professionals to diagnose hearing loss issues quickly and efficiently. 

To learn more about the Model 270+, you can visit our webpage. Or contact our customer support team on +44 (0)1865 880 846 or via email.

 

References

National Library of Medicine, The World Health Organization’s hearing-impairment grading system: an evaluation for unaided communication in age-related hearing loss. (2021). Accessed at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6351193/

World Health Organization, Deafness and hearing loss. Accessed at: https://www.who.int/health-topics/hearing-loss

American Speech-Language-Hearing Association, Degree of Hearing Loss. Accessed at: https://www.asha.org/public/hearing/degree-of-hearing-loss/

American Speech-Language-Hearing Association, Audiometric Symbols. Accessed at: https://www.asha.org/policy/gl1990-00006/

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