A Close Look at Noise Induced Hearing Loss
In the United States, the most prevalent work related injury is the noise induced hearing loss (NIHL). As the name
indicates, NIHL is the result of exposure to loud noise that is too loud or that lasts a long time. Exposure to loud noise
causes permanent damages to the hair cells that help in hearing. Hair cells are actually small sensory cells, which
converts sound energy to electrical signals that travel to the brain. When no ear hearing protection devices are used it
would lead to permanent hearing loss prevention.
Types of Noise Induced Hearing Loss
People can suffer from NIHL due to one- time exposure to loud noise or repeated exposure to loud noise over a long
period of time. The most susceptible are musicians, mine workers, construction workers, factory workers, disc jockeys
and so on. Hence, NIHL are of two types
NIHL due to Acoustic trauma
It refers to permanent ear damage due to single exposure to loud noise such as gunfire, explosions, firecrackers
and so on.
Gradually developing NIHL
It refers to permanent ear damage due to frequent exposure of loud noise for a long time.
Occupational Permissible Exposure Limit
As per Occupational Safety and Health Administration (OSHA) guidelines, the occupational permissible exposure limit for
workers is 85 decibels for 8 hours per day. An exposure, more than 8 hours could result in permanent hearing loss.
Gradually developing NIHL depends a lot on the intensity of the sound and duration of exposure. Every increase of 3
decibels doubles the intensity of sound and therefore the duration of exposure should be cut down to half. That means
maximum exposure to 88 decibels would be 4 hours a day.
Symptoms of NIHL
Ear pain and discomfort
Exposure to loud noise causes ear discomfort and pain which eases after sometime.
Temporary threshold shift
Exposure to loud noise results in temporary hearing loss in some people. Normally people regain hearing after
16 to 48 hrs.
Ringing ears or buzzing sound in the ear
Exposure to loud noise results in Tinnitus or ringing ears. Those suffering from Tinnitus would feel a constant or
intermittent ringing noise in the ears causing great distress.
Inability to hear in a noisy environment
People find it difficult to differentiate sound from background noise. Hence they are unable to hear soft sounds
in a noisy environment.
If no preventive measures or proper treatment are taken it would lead to permanent hearing loss.
NIHL is preventable unless and until people take precautionary measures. The following are some of these measures
Identify the noises that can cause great damage
Avoid hazardous sound environment
When working in noisy environment wear hearing protection devices such as noise cancelling ear muffs, ear
plugs and so on
Use communication headset in order to have normal conversation in noisy environment
When listening to loud noise, take 15 minutes quiet breaks every 2 hrs.
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