Noise-Induced Hearing Loss [NIHL]


Why should I be concerned about NIHL?

Noise-induced hearing loss is the most common permanent and preventable occupational injury in the world.

Answer Extra: 

NIHL is 100% permanent. But it’s also 100% preventable.

source: 
source: NIOSH Pub. No. 2001-103
Does the ear heal itself?

Damage to the eardrum is permanent.

Answer Extra: 

Noise-induced hearing loss primarily damages the outer hair cells in the cochlea or inner ear.  Damage can be temporary or over time, damage is cumulative and permanent.(1) A ruptured eardrum usually heals within a few weeks without treatment. Sometimes, you may need a procedure to promote healing of a ruptured eardrum, or need surgical repair for a ruptured eardrum. (2)

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sources: (1) http://www.webmd.com/news/20000616/noise-causes-hearing-loss (2) http://www.mayoclinic.com/health/ruptured-eardrum/ds00499
If a noise level doesn’t hurt my ears, or if I don’t hear ringing afterwards, was it dangerously loud?

Hearing loss typically occurs at repeated, unprotected exposures above 90 dB (about as loud as a handsaw or a forklift), but most people don’t feel pain in their ears until noise levels reach 120 dB—the noise level of a jet engine.

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After hearing loss, the most common indication of noise damage is ringing in the ears (called “tinnitus”). If you experience this regularly after work or leisure activities, you should look into HPD, ASAP.

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source: Howard Leight Noise Thermometer
How do I know if I have noise-induced hearing loss?

The telltale sign of NIHL is speech sounding distorted and less clear—but not necessarily softer. You can still hear people talking to you, but it’s harder to make out all the exact words.

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The most sensitive part of the eardrum is the region that detects high-frequency sounds. So whether hazardous noise is low-frequency (a foghorn) or high-frequency (static), a high-frequency hearing loss—where speech occurs—is the result.

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source: We Choose to Hear - And Listen
What does an ear with NIHL look like?

Noise-induced hearing loss causes no pain, no visible trauma, and leaves no visible scars.

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An ear damaged by loud noise looks just like a normal ear. Ears don’t bleed, bruise or scar; damage to the eardrum is invisible to the naked eye. In short, you can’t judge someone’s hearing by looking at his or her ears.

source: 
source: We Choose to Hear - And Listen