Critics everywhere speak with a certain awe of her "intensity of concentration and projection," as avant-garde composer John Cage put it. The Times of London noticed how she "allows herself time to probe into the meaning behind the sound." The word "spellbinding" is used. Audiences are "transported into altered states of musical awareness." Someone said, "She could develop into one of the great pianists."

Reaching back to the piano's primitive nature as a percussion instrument and stretching forward to the experiments of John Cage and Alan Hovhaness and others with prepared (modified) pianos, and beyond, to musical exploration of visual images, Margaret Leng Tan plays the piano with bolts, screws and erasers stuck between the keys. She reaches into the works and plucks the strings with her fingers, taps them with sticks. She pounds the keyboard with fist and forearm to make crashing clusters of notes.

Tan, who will give a concert at the Kennedy Center's Terrace Theater at 2 p.m. today, was staying with friends in town this week. She wanted to talk about her dinner at the White House, which she found as elaborately formal as the royal courts of Europe. She wanted to talk about her dog, who died last winter in her New York Victorian brownstone ("it's something you never really get over"). But always she wanted to talk about music, with the same passion and seriousness and sense of excited discovery that glitter in her work.

"There's a whole world of sound to be conjured up from the piano's entrails," she says, "if you're not afraid to put your hands into the piano's guts."

She is wearing jeans as she gets ready for a visit to the University of Maryland's piano archives. There is no piano in the house, but the Washington Performing Arts Society will find her one to practice on later. Her fingers are extraordinarily long.

The prepared piano dates back to Cage's "Bacchanal" in 1938, and the idea is no longer exactly avant-garde. But it is still somewhat special. For Tan the technique is just a jumping-off point.

As the first woman to earn a doctorate of musical arts at Juilliard (1971), her training has been "classical western," she says, but her heritage as a native of Malaysia raised in cosmopolitan Singapore has given her a multicultural sensibility that allows her to feel as comfortable with the xylophones and gongs of an Indonesian gamelan orchestra as with the piano.

"Since about 1981 I've worked to extend the language of piano in my own work and that of others," she says. "I'm more into ethnic music. It came on gradually, first as just an interesting project, then the work with Cage, and finally a full-time concern with the insides of the piano."

Lately she has been making music out of Korean calligraphy, transmuting the marks and spaces into notes and silences, interpreting the very density of the ink figures into sound clusters. Next January her album of Somei Satoh's music will come out: Satoh, a self-taught Japanese composer influenced by the work of the white-painted acrobatic Butoh dancers, starts with prerecorded piano music. "You play live into this wall of sound. You produce great bands of sound," Tan says. "It wipes people out."

She is right. On a recital tape, the music she plays wells up hugely, a tidal wave of percussive thunder, and dwindles to a whisper, rattles oddly, then lapses into silences that are by turns ominous, peaceful, comic. Much of this music seems to have little narrative drive, which means it calls for constant close attention. It refuses to carry you dreamily along the way those Tchaikovsky symphonic sagas do.

She opens a Satoh score. It looks like one of Proust's corrected page proofs written on music paper, the notes all but lost in a jumble of esoteric markings and scribblings, hers and his.

It is not electronic music. It goes beyond that. "The human element is what makes it. That's the magic. It all boils down to your ear, your taste. How long a bolt will you use? What width? Where exactly will you put it?"

For it is the human musician's actions, the strokings of strings that are subtly different each time, never the same twice, that interest Tan. She is excited about Cage's abandonment of control, his method of composing with the I Ching so that the sounds are predetermined by outside influences, his search for freedom from choice.

Tan, whose father is a Singapore attorney, started playing piano at 6 and came to this country at 16 to study with Adele Marcus at Juilliard. She won a Van Cliburn scholarship and other musical grants and last year a National Endowment solo recitalist award. As she learned to consciously coordinate Malaysian, Chinese and western influences, she became a familiar figure in the musical avant-garde.

She talks of Debussy often and plays his music in many of her recitals, for Debussy was a pioneer in the cross-cultural movement in art of the late 19th century, one of the first composers to take Asian music seriously and not simply use it for exotic effects. He too was influenced by the gamelan: Recall his much-quoted remark that "even Palestrina's counterpoint is child's play when compared with that found in Javanese music."

Three years ago Tan opened a John Cage retrospective concert, and last year she performed her "Sonic Encounters" at the Whitney Museum of American Art, a program that will appear on an album next year. Most recently she performed the premiere of Cage's "Four Walls."

It doesn't bother her that her Washington concert is in a rather small auditorium. "Delicate effects are lost in a big hall," she says. She will probably never play to a mass audience, for the music is, after all, a bit unconventional. But she insists it is not drily academic.

"I go for the gut reaction," she says. "Mine and theirs."