The ability to hear is one of our greatest gifts, without it the quality of our lives are significantly reduced. It’s estimated that 14,000,000 workers in the U. S. are exposed to hazardous noise levels. In fact, studies have shown that after 15 years on the job laborers will experience a significant loss hearing.
Hearing damage is caused by factors such as loudness, the amount of exposure to noise, and frequency. High frequency noise causes more damage than low frequency noise.
Noise may tire out the inner ear, causing a temporary hearing loss. After a period of time off, hearing is restored. But if exposure continues, the time it takes to restore gets longer. In many cases, by the time hearing is restored, it is time for another work shift. If this continues hearing never restores and the loss is permanent.
Normally, injury to the ears occurs in the ability to hear higher frequency sounds. Normal speech falls into this frequency. A worker may be able to hear some sounds but speech may become unclear and distorted. Workers with hearing impairment may say “I heard you, but I don’t understand what you said”
It appears that noise can increase pulse rate, blood pressure, and narrows blood vessels. Workers may complain of stomach problems, nervousness, sleeplessness, ands fatigue when they have been exposed to high noise levels.
LEGAL LIMITS ON NOISE
Under the Occupational Safety and Health Act (OSHA), every employer is responsible to provide a workplace free of excessive noise.
The details can be found in the following standards:
• 29 CFR 1910.95 – General Industry.
• 29 CFR 1926.52-Construction
PERMISSIBLE EXPOSURE LEVEL
No worker is allowed to be exposed to sound levels greater than 90 dBA without the use of hearing protection. Even so, 90dBA is not safe; 1 in 5 people exposed regularly of the levels allowed by OSHA will lose some hearing. If there are high noises levels the employer is required to reduce the noise exposure level below 90 dBA. The first step should be engineering controls, and if that fails then personal protective equipment, such as ear plugs or ear muffs, must be provided and worn.
Maximum Permissible Noise exposure
Duration per Day Exposure allowed
8 hr. 90dBA
4 hr. 95dBA
2 hr. 100 dBA
PERMISSIBLE EXPOSURE LEVEL
Normal Conversation 60dBA
Power Saw 110dBA
Pain Begins 125dBA
When 85 dBA is exceeded in the general industry standard (90 dBA in construction) for an 8 hour period the employer is required to include all exposed workers into a Hearing Conversation Program. This program must include:
• Yearly Audiometric Testing Program
• Monitoring Noise Exposure
• Hearing protection must be made available.