Magazine article Occupational Hazards

Worker Hearing: The Threat beyond the Plant Gate

Magazine article Occupational Hazards

Worker Hearing: The Threat beyond the Plant Gate

Article excerpt

OSHA standards have quieted noise in many workplaces. Safety managers must now turn to a new frontier -- environmental and recreational noise -- if they want to protect the hearing of their workers.

I HAVE SEEN PEOPLE leaving concerts with their ears bleeding," said James P. Cowan. "The exposure to those kinds of noise levels is completely voluntary."

Cowan is a certified noise control engineer who rues the fact that many people willingly subject themselves to higher noise levels off the job than they would ever tolerate while at work, Many recreational activities can cause much more serious damage to hearing than noise exposures now found in the workplace.

The manager of noise and air quality analysis at McCormick, Taylor & Associates Inc., a Philadelphia engIneering and planning firm, Cowan noted: "We have done a pretty good job protecting people in the occupational setting. The biggest problem is that once they're outside, those people are exposed to levels of noise which can damage their hearing."

As examples, Cowan pointed out that the current OSHA standard for hearing protection requires that employees wear earplugs or muffs when the noise level is over 90 decibels (dBA). Employees who have experienced a shift in their hearing must wear hearing protection when noise levels reach 85 dBA. Cowan has measured concerts that were in excess of 150 dBA.

"You can suffer acoustic trauma at noise levels above 140 dBA, when the Inner ear is literally torn apart," said Cowan, adding that additional damage to the eardrum causes some concert goers leave with their ears not only ringing, but bleeding,

Cowan, author of "Handbook of Environmental Acoustics" (Van Nostrand Reinhold, 1994), maintains that noise surrounds us all the time from various sources, but that we should take care when voluntarily subjecting ourselves to excessive levels. Some major sources of nonoccupational noise include firearms, recreational vehicles like snowmobiles and jetskis and, believe it or not, toys.

"Someone gave my son a toy telephone and when I pressed the button, the ringing was so loud I couldn't hold it up to my ear," remembered Cowan. "Young children are more susceptible to noise than adults and typically, things like cap guns and telephones generate noise which is implusive in nature."

Impulsive noise is that quick, extremely loud sound that often leaves the people exposed to it with ringing ears. Blasts from air horns at football games, the boom of a shotgun and feedback during a concert are all examples of impulsive noise.

Ringing ears, or tinnitus, is an indication that the auditory system has been overtaxed, said Cowan. If, after target practice or snowmobiling or attending a concert, your ears are ringing, you were exposed to enough noise at a loud enough level to cause some trauma to your ears. The damage may be temporary, but, over time, could become permanent.

Current Protection Standards

Some audiologists have come out against OSHA's current hearing protection standard, claiming that it is not adequate to protect all workers. Cowan said that the standard protects some 80 percent of all workers and is adequate, especially in light of the fact that many people willingly subject themselves to much higher sound levels off the job.

As for the calls from some experts that hearing protection be worn at sound levels of 70 dBA or more, Cowan claims: "That is a little extreme. We'll reach the point where people will be required to wear hearing protection to just walk out onto the street. No area is immune from noise."

In his book, Cowan lists the average noise levels for a variety of situations. …

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