Slowly the barriers are coming down. Whether in response to federal law, individual complaints or community initiatives, theaters and concert halls are finding ways to open the performing arts to long-excluded audiences.

The spread of wheelchair access and hearing- and sight-assistance programs to theaters across the country is bringing with it an often-new appreciation of the nation's 25 million or more physically disabled citizens as potential patrons. Advocates say these gains also have benefited the nation's 203 million other citizens -- the Temporarily Able-Bodied (TABs), as the handicapped community pointedly knows them.

Betty Siegel, associate house manager at Washington's Arena Stage Theater, cites her theater's wheelchair lift, installed in 1980 to circumvent the 12-step rise from street-level to the lobby.

"Not only do people in wheelchairs use the lift," she says, "but a high percentage of the elderly use it on a regular basis. We've had people who've just broken legs use the lift, people in walkers . . . If we take the wheelchair lift away, we're going to lose some of our patrons.

"The same thing with our hearing enhancement system. We have elderly patrons who would never admit to having a hearing loss who use it on a regular basis."

The picture's not all rosy. Violinist Itzhak Perlman, crippled by a bout with polio at age 4, says full physical access is still rare even in new buildings, because architects have little training in barrier-free design. "The situation is still a crap shoot," he says. "Sometimes you get it and it's right. Most of the time, unfortunately, it isn't."

Perlman, 39, also complains that Section 504 of the 1973 Rehabilitation Act -- the law that bans discrimination against handicapped people in federally funded programs -- is sometimes interpreted in ways that rob people of dignity.

"For me, 'accessible' means 'alongside and along with the general public,' " argues Perlman. "Getting into the garage or into the back of a building is not accessible."

But even Perlman agrees efforts have multiplied and attention has increased, especially in the last three to four years. Many theaters have come such a distance toward the goal that their problem has become how to get the word out to their target audiences.

"Right now," says Lucy Gregory, program administrator for Washington's National Theater Corp., "there is nothing in the advance press material that tells people when a narrated performance is, when a signed performance is. We can accommodate 20 partially sighted people for our narrated performances. We usually have only two or three people show up . . ."

The Cultural Access Network, in the process of forming, plans to help market the capital's performing arts to disabled audiences by pooling mailing lists, information and outreach programs.

But progress has not been limited to Washington.

In New York, opera singer Beverly Sills and her hearing-impaired daughter were instrumental in bringing signed performances to the City Opera in late 1982. This year, every performance is subtitled on a projection screen hanging above the scenery.

"Before," says Sills, "the deaf had to buy the most expensive seats in the house so the interpreters doing the signing could be visible, and they could only come one night out of 140. Now they can come for as little as $4. And . . . they can come any night they like."

In Milwaukee, performances of the Great American Children's Theater Company over the past two seasons have incorporated signing, Braille programs, and opportunities for audiences to touch the costumes and meet the actors. When "The Miracle Worker" played, a scale model of the set helped blind children "see" the stage. In Arvada, Colo., innovative programs cited by the National Organization on Disability have included "shadowed" performances, in which black-garbed interpreters sign behind the actors.

Are disabled audiences responsive to these kind of efforts? Yes.

By offering preferential seating, discounts and ticket purchase by mail, New York's Theater Access Project last year generated 5,839 admissions to Broadway and off-Broadway theater among disabled patrons. The $101,879 in ticket sales marked a 33 percent increase over the previous year.

The initial spur for all this activity came in 1957. That year, a presidential committee named Hugh Deffner of Oklahoma City the Handicapped American of the Year for his efforts to remove architectural barriers in his town. To receive his award, Deffner had to be lifted up the steps of a federal building by two marines.

The resulting embarrassment prodded the government into its first regulatory efforts. The Architectural Barriers Act of 1968 required access to federally owned and leased buildings -- upon new construction or major renovation. Older, unaltered buildings were exempt. There was no provision for enforcement.

In the 1970s, the laws began to have more teeth. An enforcement agency -- the Architectural and Transportation Barriers Compliance Board -- was set up in 1973.

The growth of access laws forced performing arts facilities to accommodate handicapped patrons. When the National Theater, for example, reopened after two years of extensive renovations, the building had wheelchair access to the box office, restrooms and seating at all levels. It also has a hearing assistance system, signed performances on demand and a regular narration service.

Increased public awareness also helped, and in some cases, complaints from disabled patrons speeded up the process. This was apparently the case when two Washington lawyers -- Robert Burgdorf Jr., research specialist at the National Council on the Handicapped, and Jill Robinson, a civil rights attorney from Arlington -- visited Ford's Theater in February and found the facilities lacking. (See accompanying story.)

Ford's business manager, A.J. Pietrantone, says the theater plans to upgrade its accessibility with an elevator, handicapped restrooms and an infrared hearing assistance system within the next two years. The plans hinge on the Interior Department's ability to secure congressional funding for the national historic site. Meanwhile, by early June, Pietrantone says, the theater will have removed seven end-row seats to permit unobtrusive wheelchair seating.

While he says most of the plans were already "in the works," he concedes the couple's complaints "may have hurried them on a bit.

"We weren't used to a confrontation. It kind of took us by surprise. We were trying to be creative in helping Robinson enjoy the performance . . . It was not meant to be demeaning or condescending at all."

Elsewhere, Burgdorf's and Robinson's complaints have brought little apparent result. The separate wheelchair door at the side of the Kennedy Center remains locked from the outside "to keep nonticket-holders from going in," says JoAnn Peltier, office manager for the Friends of the Kennedy Center. The Center's insurance agreement, she says, requires ushers to push wheelchairs inside the building to guard against accident. Patrons who shift to regular seats must have their wheelchairs stored by ushers -- again, she says, because of insurance regulations. In the event of a fire, she says, an usher would bring the chairs back.

Where discrimination continues, disabled people say, most often it is not willful, but the result of lack of sensitivity. Itzhak Perlman, who uses his "pull" to review building blueprints, says, "You have to put yourself in the situation where you can't walk. The minute you see a stair, you'll see . . ."

Says Charles Goldman, former counsel to the Architectural and Transportation Compliance Board: "The myth of handicapped design is that it's for the handicapped. It's not. It's for all of us. Why not put the button on the elevator a little lower? It's functional, safe and convenient. The baby carriage brigade as well as bikers benefit from curb cuts. Grab bars in bathrooms are safety features . . . The older we get, the less able we get, so we'll all ultimately be the beneficiaries. Handicapped design makes a building available for more than one generation of users."