What is an audiogram?
During an audiometry hearing test, audiologists will look for the softest volume of sound which the listeners can hear at different frequencies (low pitches to high pitches). An audiogram is a chart that contains a visual representation of the outcome of that test. It can diagnose the degree and type of hearing loss in each ear. The results from the audiogram help the audiologist to understand and counsel their patients on hearing related issues.
On the audiogram, you will see a series of O and X, which represent the hearing measured through air conduction. The red O shows how well you can hear in your right ear and the blue X shows how well you can hear in your left ear.
You will also see a series of < [ and > ]. The brackets represent the hearing measured through bone conduction which tell us how our hearing nerve is hearing. < [ is the result from your right ear measured with bone conduction and > ] is the result from your left ear measured with bone conduction and
On the audiogram: the X-axis (horizontal) measures the frequency of the sound while the Y-axis (vertical) measures the intensity of the sound.
The X-axis (horizontal) measures the frequency of the sound. Frequency, or pitch, is measured in hertz (Hz), from low to high pitched. Low pitched sounds are on the left and higher pitched sounds are on the right, just like on a piano keyboard. For example, low-frequency sounds include the sounds of deep male voices and high-frequency sounds include the sounds of bird chirping.
The Y-axis (vertical) measures the intensity of the sound. Intensity, or loudness, is measured in decibels (dB), from quiet at the top to loud at the bottom.The louder sounds are toward the bottom and softer sounds are toward the top of the graph. The lower down the chart, the higher the decibels and the louder the volume. For example, low-decibel sounds include whispers and high-decibel sounds include airplane engines.
The degree of hearing loss is determined by the location of the symbols on the audiogram. If the symbols are located mostly at the top of the audiogram, below 25dB HL, then hearing is considered normal. The higher up the y-axis, the more sensitive the hearing. However, if the threshold falls below this 25dB HL line, then a hearing loss is present. The lower the symbols are plotted on the audiogram, the louder the sounds needed to be before the listener can hear them, and the poorer the hearing sensitivity is.
Speech banana is a banana-shaped range on an audiogram. It describes the area where most phonemes or sounds of human speech occur. The speech banana covers the frequencies and decibels that are needed to understand average conversational speech.
Audiogram and Everyday Life
So now we understand how to read an audiogram, how does the reading apply to our everyday listening?
Hearing differs from person to person. A person can have 2 ears with different hearing. A person with normal hearing sensitivity can hear sounds below 25 dB. If a person hears when sounds are above 25 dB, the person has some hearing loss. Different degrees of hearing loss has different implication on everyday life and communication, which will be discussed below:
Five Degrees of Hearing Loss:
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Mild Hearing Loss (26-40 dB)
People with a mild hearing loss may have difficulty detecting soft sounds and hearing soft spoken people. They are often able to hear the loud vowel sounds (e.g., A, E, I, O, U), but may miss some of the softer consonant sounds (e.g., s, th, f). They may have to ask people to speak up or repeat themselves, and have difficulties listening to conversation especially in noisy environments.
Moderate Hearing Loss (41-55 dB)
People with a moderate hearing loss may have difficulty with some consonant sounds as well as vowel sounds. They often comment that they can hear, but can’t always understand.
Moderately Severe Hearing Loss (56-70 dB)
People with a moderately severe hearing loss may have major difficulty detecting speech sounds without hearing aids. Listening and communication start to become very challenging. They may have to ask people to speak up and repeat themselves loudly.
Severe Hearing Loss (71-90 dB)
People with a severe hearing loss may have major difficulty detecting any speech sounds. They may only react to very loud sounds. Without hearing aids or cochlear implants, speech is basically inaudible.
Profound hearing loss (above 91 dB)
People with a profound hearing loss can only hear extremely loud sounds like airplane engines or fire alarms. Without hearing aids or cochlear implants, speech is inaudible. They can hardly detect sounds in the environment and that could be dangerous.
Make it stand out.
Some examples of different audiograms:
You will find a line connecting your symbols (threshold levels), right and left ear respectively. Areas above the line are the sounds that you cannot hear, while areas below the line are the sounds you can hear. A line lower on the chart indicates a more extreme hearing loss.
Below is an example of an audiogram indicating normal hearing sensitivity. You can see all symbols are within 25dB and a line connecting the threshold levels for both ears at the top of the audiogram indicating both ears hearing are within normal hearing sensitivity. This means that very soft sounds like leaves rustling and water drops can be heard.
Below is an example of an audiogram indicating a sloping hearing loss in the both ears, often seen in age-related hearing loss. You can see a line slopes downward for higher frequencies. This means that the person can hear soft sounds in the lower frequency sounds, but start to have problems hearing higher frequency sounds. A common comment from people with high tone hearing loss is “I can hear sound, but I cannot hear what other people are saying.” The reason for that is because the lower frequency sounds are responsible for loudness while the higher frequency sounds are responsible for clarity. For people with sloping hearing loss, they may start to have difficulties understanding especially in noisy environment.
On the audiogram, you will see a series of O and X, which represent the hearing measured through air conduction. The red O shows how well you can hear in your right ear and the blue X shows how well you can hear in your left ear.
You will also see a series of < [ and > ]. The brackets represent the hearing measured through bone conduction which tell us how our hearing nerve is hearing. < [ is the result from your right ear measured with bone conduction and > ]is the result from your left ear measured with bone conduction and
Read More: Three Types of Hearing Loss
In patients with sensorineural hearing loss, both air conduction thresholds (O and X) and bone conduction thresholds (< [ and > ]) are greater than 25 dB in one or both ears and the bone conduction thresholds are at the same or similar levels. The loss results from a problem from the inner ear or the auditory nerve.
In patients with conductive hearing loss, air conduction thresholds (O and X) are greater than 25 dB, but bone conduction thresholds (< [ and > ]) are all within 25 dB. Bone conduction thresholds are better than the air conduction thresholds by 10 dB (air-bone gap). This loss results when there is a problem in the outer or middle ear, preventing from getting to the inner ear. For example, earwave impaction or middle ear fluid may weaken the sound traveling to the inner ear.
In patients with mixed hearing loss, both air conduction thresholds (O and X) and bone conduction thresholds (< [ and > ]) are greater than 25 dB. Bone conduction thresholds are better than the air conduction thresholds by 10 dB (air-bone gap). This loss results when there is a problem in the outer or middle ear and the inner ear or the auditory nerve.
If you are concerned about your hearing and may be experiencing any signs of hearing loss, see an Ear-Nose-Throat Doctor or an audiologist for consultation. Timely and appropriate intervention is very important.