Understanding Your Audiogram
What is an audiogram?
An audiogram is chart of a person’s hearing ability. When an audiologist gives you a hearing test, your hearing is checked at different frequencies and volumes. The result of the test is recorded as an audiogram curve.
Audiogram with Headphones
The person whose hearing is being tested will be in a soundproof room, wearing headphones. The test can be administered in two ways. The first is when sound is transmitted through the headphones by an audiologist, and the subject presses a button when they hear a sound. The results of the test are plotted on an audiogram. The second method uses bone conduction.
In a bone-conduction test, a vibrating device rests on the bone behind the ear, and is held in place with a metal band stretched over a person’s head. Sound is transmitted through the device via direct vibration of the bone. The vibrations are carried through the bones and tissues, through the skull, directly to the cochlea. This test bypasses the entire outside and middle ear areas, allowing the audiologist to test the sensitivity of the inner ear only.
Reading the Audiogram: Horizontal Scale
The horizontal scale on the bottom of the audiogram indicates the frequency (pitch), measured in hertz (Hz). Like a piano, the frequency moves from low to high, with the low frequencies (e.g. the hum of an engine) on the left, and higher frequencies (e.g. chirping of birds) on the right.
Reading the Audiogram: Vertical Scale
The vertical scale represents volume – how loud each frequency was, from soft (top) to loud (bottom). The volume is measured in decibels (dB). For healthy ears, sound starts at 0dB and the pain threshold is 110dB. It is important to note that 0dB is not the absence of sound; it is the softest sound that a person with normal hearing would be able to hear 50% of the time.
Your Hearing Threshold and Range
A person’s hearing threshold is the softest sound they can hear at least 50% of the time. When the audiogram is complete, the audiologist will be able to tell you how well you hear at different pitches. If the audiogram indicates some hearing loss, the audiologist will be able to tell you which part of your ear (outside, middle or inner ear) is causing the impairment.
The typical hearing ranges for adults are:
-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.