"IT WOULD be very hard for me to tell a lie in sign language," says Linda Bove -- in sign language. "If I say something and don't mean it, my face gives me away. From what people tell me, the spoken word can be used as a sort of screen. There's a lot that you're not using -- no body, no face.You can get a lot more information in sign language."

In "Children of a Lesser God," which opens Wednesday at the National Theatre, Linda Bove plays Sarah Norman, a deaf woman who communicates exclusively in sign language, proudly refusing to learn to speak or lip-read because she will only do what she can do well. Nationally known for her work in sign language on "Sesame Street" and as a member of the National Theatre of the Deaf, she has no firsthand knowledge of the spoken word. In a telephone conversation last week, she spoke through a sign-language interpreter.

Asked whether she thinks a woman with hearing could play the role of Sarah, she answers, "No, no, definitely no." In fact, "Children of a Lesser God" was written for actress Phyllis Frelich, a founding member of the National Theatre of the Deaf, after she complained to playwright Mark Medoff that there were no roles she could play in what is called "the hearing theater." The play, which last year won three Tony awards including "Best Play," will mark its first anniversary on Broadway tomorrow.

Bove's co-star, Peter Evans, uses sign language throughout the play, but to him it is a foreign language. He plays Linda Bove's teacher in the first act, and becomes her husband in the second. There are seven characters in the play, but it focuses tightly on the struggle for dominance and/or autonomy between the two central characters. Evans translates all of Bove's signed dialogue into spoken English and all of his own spoken dialogue into sign language as part of the dramatic action. Fortunately, Evans believes, his character is not supposed to be perfect in sign language: "Sometimes people in the audience come backstage and tell me that I have just the right kind of awkwardness for the role," he says. "I thank them, of course, but it's not all acting."

The players were reached by telephone in Philadelphia, where the touring production of "Children of a Lesser God" played before coming to Washington. Evans was able to communicate directly by phone.

"It's like acting in two languages simultaneously," says Evans, who has been playing the role of James Lees for more than four months on the play's national tour. "I began five weeks of intensive study last September, then three weeks of rehearsal. But it's something like going to Paris for three months, studying French and then going on stage with the Comedie Francaise."

Of course, "Children of a Lesser God" is more than a play about deafness. For Bove, the play does have a message on various levels and one that she considers significant, but she believes "it is basically a love story. It happens that one person in this story is deaf and that they communicate in sign language, but it is really a story about these two people. You learn something about the deaf, but that's not the whole story of the play."

Director Gordon Davidson agrees. The play, he says, "is not, finally, about deafness and hearing, but about human relationships, about how we try to make people over in our own image if we are forceful personalities. It's about the difficulty of helping a person find a sense of self and growth, rather than force growth in a particular direction. Hearing and not hearing become metaphors for a longer look at human relationships."

Playwright Mark Medoff cringes a little when he is asked whether the play is about communication problems. "I suppose it is," he says, "But I hope it's not that cut and dried. There are no new things, but we should at least try to freshen them up a bit, and I hope that with the element of sign language we have freshened up the cliches about communication problems. At least, the effort involved in the use of sign language suggests the effort that two people must make in order to communicate. It requires an enormous effort, even when the people do not use two basically different languages. Of course, I never sit down to create metaphysical structures for a play. They just appear -- somewhere in the rewriting process, they emerge, and when you notice them you just try to focus and clarify them."

The proces of producing "Children of a Lesser God" began during a workshop at the University of Rhode Island, where Medoff was the guest playwright and Frelich was a guest actress (playing the part of the wall in "The Fantasticks").

"Her husband, Bob Steinberg, was my set and lighting designer," Medoff recalls. "At first, I knew only that he was married to a deaf woman, who used to be with the National Theatre of the Deaf, now retired and raising two children. I was told she was a terrific actress. Then I met her, we started to communicate with one another, and I became obsessed with wanting to learn her language. One of the things she told me was that there really were no parts in what we call the hearing theater for deaf actors. Simple because I liked her a lot, I said I would write a part for her."

He began working on the play in the summer of 1978 at the University of New Mexico, Las Cruces, where he is the head of the drama department, and in January 1979 Frelich and Steinberg came to New Mexico for workshops on the original script. At that point, Medoff says, the script was "promising but unwieldly." Then director Davidson became interested, collaborated with Medoff on revisions, and brought the play to the Mark Taper playhouse in Los Angeles, where he is the resident director. Broadway producer Emanuel Azenberg saw the Los Angeles production and recalls that "my responses were very visceral . . . I imagine that it I had been shown that play in an original script it would have been very difficult to judge its quality." After Medoff and Davidson collaborated on further changes, the show was ready to triumph on Broadway.

If his career is ever divided into periods, Medoff believes, the crucial division will be before and after "Children of a Lesser God."

"While I was working on this play," he says, "I became more humane in terms of attitudes toward the people I was writing about. In all of my earlier work, I felt great anger and antagonism, which was projected through the characters in a way that made it hard for the audience to find them sympathetic.

"As I worked with these people, my relationships began to change, not only to my characters but to students and members of the faculty and the acting company. The feelings were so warm, the sharing so full that I found myself feeling very positive, all the time. Phyllis and Bob and I became and still are brothers and sisters, and Gordon has become one of my most beloved friends, with an extremely positive working relationship. I was 39, at the time, and I wasn't going through any particular crisis that I know of, but I think I was coming down from the frustration of our collective failure of the would-be revolution of the late '60s and early '70s. Now, I focus a great deal on my family. I have a wife I love and three small children, and somehow that relationship, that desire to focus on the family, a unit currently in disfavor, had a very positive influence on me.

"The play I am writing now is rough and tough. Very brutal things happen in it, but I think of it as a love story. Some people who know my work wish I would go back to being nasty, but something will have to happen first to change my life."

Evans said he was "amazed by the whole experience" when he first saw the play in New York, with John Rubenstein in the role that he is now filling. "I had never known anything about deafness, but you can learn a lot in 2 1/2 hours. After the show, I went out in the lobby and I saw people using only their mouths to communicate, and I had this moment of culture shock. How bland it is, I thought: These people are communicating through just one sense, not using their hands or bodies. I began to realize how little of our communication resources we regularly use."

Later he would learn much more -- including the fact that there are regional dialects in sign language, as he discovered from his work with understudy Freda Norman. "At first, I had trouble understanding Freda's signing," he says. "Linda's is much faster and close to her face. Then someone explained to me that Freda is from Virginia and speaks sign language with a Virginia accent, while Linda uses a New York accent."

For Evans and Bove, or both of them, the Washington run of the play has a special meaning because of the presence of Gallaudet College in this city. Bove, who studied at Gallaudet, says, "it will be like a homecoming. I know many people from Gallaudet, teachers and alumni who are living in the Washington area." For Evans, who worries a bit about keeping his sign language up to par, there is "some anxiety in knowing that we will be playing to audiences loaded with experts on sign language."