More than 300 people packed the Prince George's County Council's chamber in Upper Marlboro last night for a hearing that became a debate over whether the Wild World Amusement Park should be allowed to add roller coasters, an amphitheater, another swimming pool and a campground.

The proposed additions drew vehement opposition from residents of the Kettering area, who have complained to the council since 1982 about noise at the park near their homes and traffic problems it creates on Central Avenue.

Attorneys for the park, which begins its summer season May 18, defended its operation and argued that the council should grant rezoning to permit the added amusement facilities.

The backers of the park's request included teen-agers wearing "I Love Wild World" hats and buttons who poured into the County Administration Building in Upper Marlboro from six buses provided by the park's owners as part of a day of orientation activities for new employes.

Wild World, which employs 500 young people every season, is the largest single seasonal employer of youth in Prince George's County, park officials said.

Some residents who live near the park, including Agnes Bowersox and Kathleen Smith, complained that several incidents of excessive noise have disturbed their community.

"Wild World's policy never changes," Bowersox said. "Anything for a buck and to hell with the neighbors."

Smith said she filed a complaint about the park in 1982 over a particularly loud concert given there by country music recording artist Charlie Daniels.

"With my windows shut, with my storm windows shut, we still had music [from the park] in my house," she said.

Attorneys for the park said that both existing and proposed facilities there meet state noise guidelines. John Lally, one of the attorneys, said careful testing will be undertaken with the aim of keeping the "scream levels" from the roller coaster within mandated sound levels.

"If we could put a bubble over 500 acres, perhaps that would prevent the two times in three years we've had a problem," Lally told the council.

Lally said the proposed open-air, 3,000-seat amphitheater for small concerts would operate on the order of the Carter Barron Amphitheater in Rock Creek park or the Wolf Trap Farm Park in Fairfax County.

"If it's good enough for Northwest Washington, hopefully we can be [as good a neighbor] in the Kettering-Largo area," he said.

None of the seasonal employes, some who said they lived as far away as Baltimore, spoke at last night's hearing, but many carried hand-lettered signs and said in interviews that they are concerned about the park's future.

"We felt it was important for them to understand," said V. Paul Zanecki, one of Wild World's owners, who is a law partner of Lally.

Some state legislators spoke on behalf of the Kettering community, but emphasized that it is up to the council to determine what controls should be imposed.

"There should be no doubt in anyone's mind that further expansion of this operation will have a serious and negative effect on the quality of life for the citizens of the Kettering community," Del. Jerry E. Perry said. "I ask you to reject any proposals for the expansion of Wild World."

The council took no action last night.