As speech pathologists, it is well within our scope of practice to help families understand how to read an audiogram and interpret the results of formal hearing evaluations. An audiogram is a chart that shows how well a person hears different sounds. Recently updated, this post begins by explaining how to read an audiogram, defining the measures used in formal hearing testing. It then covers the symbols used on an audiogram, followed by a discussion on the three different types of hearing loss.
How to Read an Audiogram: Understanding Frequency, Decibels, and Thresholds
Frequency
Frequency, also known as Hertz (Hz), denotes sound pitch, ranging from 250 Hz to 8000 Hz. An example of a low pitch would be the sound of thunder; for a midrange pitch, an example would be a telephone ring. A high pitch example would be the sound of cymbals clanging.
The bottom of the audiogram shows frequencies, or pitches, of sounds from low (125 Hz) to high (8000 Hz). Think of it like the keys on a piano, with low notes on the left and high notes on the right.
Decibels
Decibels (dB) mean intensity or loudness; and it is measured from 0 dB through 110dB. Normal conversational speech is about 45 dB. It is important to note that 0dB does not mean the complete absence of sound, but rather it is the softest sound that a person with normal hearing ability would be able to detect at least 50% of the time.
The side of the audiogram shows the loudness of sounds, measured in decibels (dB). The higher the number, the louder the sound. Zero at the top represents very soft sounds, and the numbers go down to 120, which are very loud sounds.
Threshold
We call the softest level at which your child can hear the threshold. In a hearing evaluation, an audiologist tests frequencies from low to high decibels until the client hears each pitch. The audiologist then documents the threshold for each frequency on the audio gram. When testing is completed with headphones, it is called “air” thresholds because the sound must travel through the air of the ear canal to be heard.
How to Read an Audiogram: Making Sense of Symbols
Your child’s audiogram should have a box explaining what the symbols used on the diagram represent. The right ear is marked with an O, and the left ear with an X to indicate air conduction test thresholds.
An audiologist uses a bone conduction test to determine the type and extent of hearing loss by assessing the inner ear’s function independently of the outer and middle ear. This helps differentiate between conductive, sensorineural, and mixed hearing loss. When using bone conduction, the audiologist places a small device behind the child’s ear, secured by a metal band. This device sends sounds via direct vibration of the bone and specifically tests the sensitivity of the inner ear. A < symbol denotes the right ear and a > symbol indicates the left ear’s responses to bone conduction. If testing reveals a hearing loss, the audiologist will compare results of air and bone conduction testing to identify the type of loss.
Audiogram of Conductive Hearing Loss
This particular audiogram is for someone with conductive hearing loss. Let’s break it down so it’s easy to understand.
- Air Conduction: The X’s on the chart show how well sound travels through the outer and middle ear. In this audiogram, the X’s are all around 60 dB across different frequencies. This means that sounds need to be quite loud for the person to hear them, indicating hearing loss.
- Bone Conduction: The arrows at the top of the chart represent bone conduction, which measures how well sound is heard directly through the inner ear, bypassing the outer and middle ear. In this audiogram, the bone conduction levels are normal, shown by the arrows near 0 dB.
The gap between the X’s (air conduction) and the arrows (bone conduction) indicates a conductive hearing loss. This means the problem is in the outer/ middle ear, where sound is not efficiently conducted to the inner ear. In simpler terms, the audiogram shows the inner ear works fine, but there’s an issue in the outer/ middle ear.
Understanding and Supporting Children with Conductive Hearing Loss
A conductive hearing is sometimes treatable with medication or surgery and is typically temporary. If your child has a conductive loss during peak learning, you may notice limited responses to language and little talking. While your child receives treatment, seize chances to let them watch your lips form sounds and use visuals. Even with one affected ear, they perceive speech as if underwater.
Audiogram of Sensorineural Hearing Loss
This image is an audiogram showing the results of a hearing test for a person with sensorineural hearing loss.
- Right Ear (Red Circles and Brackets): The right ear’s air conduction thresholds (red circles) show that this ear can hear sounds at higher pitches with less difficulty than lower pitches. The bone conduction thresholds (red brackets) follow a similar pattern, confirming the sensorineural nature of the hearing loss.
- Left Ear (Blue Squares and Brackets): The left ear’s air conduction thresholds (blue squares) indicate a significant hearing loss across all frequencies. The bone conduction thresholds (blue brackets) are similar to the air conduction thresholds, which is characteristic of sensorineural hearing loss.
Understanding and Supporting Children with Sensorineural Hearing Loss
A sensorineural loss occurs when the inner ear is not properly receiving sounds. Your child’s audiogram would indicate an air conduction threshold and bone conduction threshold with the same amount of hearing loss. Several factors cause this loss, including aging, prolonged exposure to loud noises, viral infections, disrupted blood supply to the ear, metabolic disturbances, accidents, and genetic predisposition. About 90% of people with hearing impairments have this type of loss. Regrettably, medications or surgeries cannot treat it, but hearing aids can enhance responses to sounds. Those with a severe hearing loss may benefit from a cochlear implant.
Audiogram of Mixed Hearing Loss
- Red Circles (Right Ear Air Conduction): These indicate the hearing levels for the right ear when sound is delivered through the ear canal. The red circles mostly show moderate hearing loss across frequencies.
- Blue Crosses (Left Ear Air Conduction): These show the hearing levels for the left ear with sound delivered through the ear canal. The blue crosses indicate moderate hearing loss across most frequencies.
- Red Brackets (Right Ear Bone Conduction): These brackets represent the hearing levels for the right ear when sound is delivered directly to the inner ear (bypassing the outer and middle ear). They show better hearing compared to air conduction, indicating a conductive component to the hearing loss.
- Blue Brackets (Left Ear Bone Conduction): These brackets indicate the left ear’s hearing levels with sound delivered directly to the inner ear. Similar to the right ear, they show better hearing levels compared to air conduction, indicating a conductive component.
- Overall Pattern: The audiogram shows a combination of conductive and sensorineural hearing loss, known as mixed hearing loss. Your child may have a sensorineural hearing loss and develop a conductive loss due to fluid or wax in the ears. This is evident because the bone conduction thresholds (brackets) are better than the air conduction thresholds but still show hearing loss.
Understanding and Supporting Children with Mixed Hearing Loss
Supporting children with mixed hearing loss involves a comprehensive approach that includes regular audiological evaluations, the use of hearing aids, bone conduction devices, or cochlear implants, and the creation of an Individualized Education Plan (IEP) with classroom accommodations and special education services. Speech therapy is essential, with parents and caregivers involved in reinforcing strategies at home. Communication can be enhanced through sign language and visual supports, while environmental modifications like acoustic improvements and assistive listening devices reduce background noise. Emotional and social support, including counseling and social skills training, are crucial, along with continuous monitoring and adaptation of strategies as the child’s needs evolve.
How to Read an Audiogram: Hearing Ranges
The following indicates results for the average ADULT. Interpreting results for children is challenging due to variable responses, but these numbers provide a general sense of severity.
- -10 dB to 25 dB = Normal range
- 26 dB to 40 dB = Mild hearing loss
- 41 dB to 55 dB = Moderate hearing loss
- 56 dB to 70 dB = Moderately Severe hearing loss
- 71 dB to 90 dB = Severe hearing loss
- over 90 dB = Profound hearing loss
How to Read an Audiogram: Next Steps
After an evaluation using headphones in a sound-proof booth setting, your audiologist should be able to answer the following questions based on test results:
- How well does my child hear at low, medium, and high pitches?
- Does my child have a hearing loss?
- If my child has a hearing loss, what part of the ear is affected: outside, middle, or inner?
How to Read an Audiogram: Take Away Points
In conclusion, understanding how to read an audiogram is an essential skill for speech pathologists, enabling us to better support families and collaborate effectively with audiologists. By comprehending the measures and symbols used in formal hearing evaluations, we can accurately interpret audiograms and provide informed guidance. This knowledge is crucial in identifying the type of hearing loss—whether it be conductive, sensorineural, or mixed—and in developing appropriate intervention strategies. Empowering families with this understanding enhances their ability to make informed decisions about their child’s hearing health and overall communication development.
For more details about audiological hearing evaluations, read my post: Why Does my Child need a Diagnostic Hearing Evaluation?
Nanette Cote is an ASHA certified speech pathologist, published author, and private practice business owner with 30 years experience.
