Standing on the stage of the Kennedy Center's Terrace Theater Wednesday night after a concert of her enigmatic music, Pauline Oliveros was answering questions from the audience, cutting the figure of a sturdy, slightly weathered and middle-aged Earth Mother.

Why, inquired a young man, did she perform on her accordion in bare feet?

"One reason is symbolic: because what it means is 'to serve,' " she explained, sounding supremely confident of the doctrinal foundation of this habit. "Another reason is that I can hear better. I feel the vibrations of the music through the floor. I am better grounded."

This may sound bizarre in print, as may her compositional nomenclature -- with all the talk of "attentional strategies" and "meditational series" instead of sharps and flats. But words aside, throughout the evening there were a certain raw power and integrity in both the composer and in what she composes.

These works -- improvised by the players following guidelines that Oliveros writes in prose -- are like giant tonal clusters, going on for minutes, as groups of instruments loosely explore the extreme ranges of their sonorities. For instance, in "Earth Ears," the two accordions drone away at the front of the stage, the two violins behind them scratch away in ghostly relief, and the two pianos thunder away in murky arpeggios, none of this so much articulated as roared.

It is music that is not so much moving through time as suspended in it -- music in which such developmental elements as harmony, rhythm and structure are of minimal import.

The most extreme example was "The Tuning Meditation," in which singer Barbara Noska came on stage, assumed the traditional meditational seating position and started incanting wordless tones, with members of the audience asked to start doing the same, until in a few minutes "the theater is filled with sound." And that's all there is to it.

Typically, an Oliveros piece is more complicated, especially in "The Well," a lyric, often delicate three-movement work memorably choreographed by Deborah Hay and danced by her Wednesday night with real eloquence.