A federal appeals court yesterday upheld an Occupational Safety and Health Administration regulation designed to reduce the hazard of noise in the work place -- one of the few standards promulgated by the agency since President Reagan took office.

The decision by the full eight-judge 4th U.S. Circuit Court of Appeals reversed a 1984 ruling by a three-judge panel of the court, which had declared the rule invalid on an appeal from the Forging Industry Association.

At OSHA's request, the full court reheard the case and unanimously upheld the regulation.

OSHA has imposed noise limits since the agency was created in 1971. The rule set a maximum exposure of an average of 90 decibels weighted over an eight-hour period. It also required the employer to reduce the noise level or provide hearing protectors if the limit is exceeded.

When studies revealed many employes suffered hearing loss when exposed to noise levels below the 90-decibel limit, OSHA considered reducing the limit at which ear protection is required to 85 decibels.

While considering the change, OSHA issued a regulation that left the 90-decibel limit intact, but required employers to determine which workers are exposed to noise above 85 decibels and take protective measures at that level.

The provisions apply to all workers covered by OSHA rules except those in construction, agriculture, and oil and gas well drilling. OSHA estimated compliance with the regulation would cost $210.3 million a year, or $41 per employe.

The agency published the amendment as a final rule on March 8, 1983, after nine years of hearings and studies.

The Forging Industry Association argued that hearing loss can result from age or activities outside the work place, such as listening to loud music.

But the court found that OSHA relied on thorough scientific research on hearing losses suffered in the work place in designing its proposal.

"Nonoccupational noise of that intensity sustained over a period of eight hours each day is hard to imagine," the court said.

After reviewing the studies, OSHA concluded that the new regulation would reduce the number of hearing problems by 212,000 in the 10th year, 477,000 in the 20th, 696,000 in the 30th and 799,000 in the 40th.