Your hearing is measured in a scale of decibels (dB) compared to ‘normal’ hearing. This scale is used to evaluate whether you have hearing loss, and if so, to what degree.
During your hearing examination, your hearing care professional will test your hearing and present the results in an audiogram (see below).
Decibels (dB) measure the intensity of sound. The scale runs from the faintest sound the human ear can detect, which is labeled 0 dB, to more than 180 dB, the noise at a rocket pad during launch. Most experts agree that continual exposure to more than 85 decibels is dangerous. Recent studies show an alarming increase in noise related hearing loss in young people.
Approximate examples of decibel levels:
- Faintest sound heard by ear – 0 dB
- Whisper, quiet library – 30 dB
- Normal conversation, sewing machine, typewriter – 60 dB
- Lawnmower, shop tools, truck traffic – 90 dB
- Chainsaw, pneumatic drill, snowmobile – 100 dB
- Sandblasting, loud rock concert, auto horn – 115 dB
- Gun muzzle blast, jet engine (such noise can cause pain and even brief exposure injures unprotected ears) – 149 dB
- The Occupational Safety and Health Administration’s limit for noise without hearing protectors – 140 dB
Pitch is the frequency of sound vibrations per second measured in hertz or kilohertz, and duration. A low pitch, such as a deep voice or a tuba, makes fewer vibrations per second than a high voice or violin — the higher the pitch, the higher the frequency. Loss of high-frequency hearing also can make speech sound muffled.
Levels of hearing loss
This scale shows different levels of hearing loss (HL).
Normal hearing (<25dB HL)
Mild (26-40dB HL)
You have trouble hearing or understanding soft speech and whispers, or speech over background noise
Moderate (41-55 dB HL)
You have trouble hearing or understanding regular speech up close or regular speech in a quiet office environment
Moderately severe (56-70 dB HL)
You have trouble hearing or understanding everyday conversations or a telephone ringing
Severe (71-90 dB HL)
You can only hear loud sounds such as very loud speech, sirens or a door slamming
Profound (90+ dB HL)
You have trouble hearing sounds such as a motorbike or power tools
The degree of hearing loss is an important factor when choosing hearing aids. Not all hearing aids will suit all degrees of hearing loss.
An audiogram is a visual representation of your hearing. During the hearing test, your hearing healthcare professional will plot the results into the audiogram.
This is a typical audiogram for a person with normal hearing:
Information on this page obtained from the ReSound web site: www.gnresound.com, 2011.