Blog #7 Preventing noise induced hearing loss with hearing protection

Blog 7: Preventing noise induced hearing loss with hearing protection 

The ear has three main parts: the outer, middle, and inner ear. The outer ear which is the part you can see leads into the ear canal. The eardrum separates the ear canal from the middle ear. Small bones in the middle ear help carry sound vibrations to the inner ear. The vibrations become nerve impulses, which the brain then translates to the sounds we hear like music, voices, and so forth.

Loud noises kill the nerve endings in the inner ear. Constant exposure to loud noise destroys nerve endings giving them no time to recover and a result, the number of nerve endings decrease along with your hearing. There is no known way to bring back dead nerve endings; this damage is permanent, along with the hearing loss.

“Noise is one of the most common causes of hearing loss, and one of the most common occupational illnesses in the United States. A single shot from a large caliber firearm, experienced at close range, may permanently damage your hearing in an instant. Repeated exposures to loud machinery may, over an extended period of time, present serious risks to human hearing.”

-    http://www.betterhearing.org/hearingpedia/hearing-loss-prevention/noise-induced-hearing-loss

Sound is measured in decibels. Sounds of less than 75 decibels, even after long exposure, usually don’t to cause hearing loss. However, long or repeated exposure to sounds at or above 85 decibels can cause hearing loss. The louder the sound, the shorter the amount of time it takes for NIHL to happen.

Some average decibel ratings of everyday sounds:

-    Firecrackers and firearms - 150 decibels

-    Sirens - 120 decibels

-    An MP3 player at maximum volume - 105 decibels

-    Motorcycles - 95 decibels

-    Noise from heavy traffic - 85 decibels

-    Normal conversation - 60 decibels

-    The hum of a refrigerator - 45 decibels

“Habitual exposure to noise above 85 dB will cause a gradual hearing loss in a significant number of individuals, and louder noises will accelerate this damage. For unprotected ears, the allowed exposure time decreases by one half for each 5 dB increase in the average noise level. For instance, exposure is limited to 8 hours per day at 90 dB, 4 hours per day at 95 dB, and 2 hours per day at 100 dB. The highest permissible noise exposure for the unprotected ear is 115 dB for 15 minutes per day. Any noise above 140 dB is not permitted.”

-    http://american-hearing.org/disorders/noise-induced-hearing-loss/

Hearing protectors like earmuffs or earplugs decrease the intensity of sound. Earplugs are small inserts that fit into the outer ear canal. Effective earplugs totally block the ear canal with an air-tight seal. Earmuffs fit over the entire outer ear forming an air seal. Effective earmuffs must be snugly sealed covering the entire circumference of the ear canal.

Earplugs or muffs can reduce noise by 15 to 30 dB of sound. However, earplugs are better protection against low frequency noise like a jackhammer, and earmuffs are better protection against high frequency noise like the sound of an airplane taking off. Simultaneously using earplugs and muffs can add 10 to 15 dB more protection than using either alone. Combined use should be considered when noise exceeds 105 dB.