Michael Harrison's harmonically tuned piano.

Anyone involved with classical music has probably heard numerous syrupy descriptions of music as the connection between mortal life and the gods. And for much of its history, music of many cultures has often been a vehicle for people to express their spirituality. In Western music, while more vernacular styles were a natural outgrowth of such traditions, "classical" structures stayed closely tied to, if not a religious institution, at least an overwhelmingly spiritual perspective. To nontraditionalists such as Arnold Schoenberg and John Cage, the rigid rules of harmony and counterpoint created to keep music universally spiritual had ended up enslaving it, and they thus took it upon themselves to liberate sound. What resulted was a disconnect between music's preordained sacred function and the new esthetic.

With the arrival of the reactionary minimalists, not only was tonality stubbornly re-established, but there was a newfound desire to reconnect music to a higher purpose. But this time they were not simply restricted to addressing Christian ideals. Composers such as LaMonte Young and Terry Riley found inspiration in North Indian Classical music's alternate tuning systems, exotic instruments and peaceful selflessness. The appeal of these esthetics has remained alive for many of minimalism's disciples, including Michael Harrison, whose aptly titled Revelation: Music for the Harmonically Tuned Piano will be performed this weekend as part of the American Festival of Microtonal Music.

A protege of both Young and Riley as well as a student of North Indian vocal music master Pandit Pran Nath, Harrison has developed his own personalized piano tuning for his 90-minute solo piano piece based on the naturally occurring overtones, similar to the system designed by Pythagoras. The result, at first, to both trained and untrained ears is that the notes sound out of tune, like an extremely old and neglected honky-tonk piano. But upon more careful inspection, one can hear that just the opposite is the case. Each string has been carefully tuned to create mathematically accurate ratios.

Harrison believes that by embracing the irregularities of a harmonically tuned piano, he has taken the next step in what Schoenberg described as "the emancipation of dissonance." In Schoenberg's case, he threw the tonal system of composition away and focused on intervals and the dissonance it created. In Harrison's case, he has rejected equal temperament tuning in order to achieve a similar goal.

When discussing the piece, Harrison shows a mathematician's fascination with numbers and ratios, and has esoteric goals. But when he plays it (he is also a pianist), it is a whole different story. The melodies are simple and lyrical and seem to melt into pools of sound?what Harrison calls "tone clouds." In these sections, Harrison becomes possessed by a certain kernel of music and plays it over and over, pounding on the keys and letting the clashing overtones create their own melodies and rhythms high above what is being played. Often it sounds as if there is a whole orchestra of acoustic and electronic instruments accompanying the piano. Literal waves of sound wash over the audience and it is nearly impossible to resist closing your eyes and just letting Harrison take you with him. And after sitting through 90 minutes of this tuning, regular pianos seem colorless.

This weekend's performance marks the first time that the piece will be performed with a soloist other than Harrison himself. Grammy-nominated pianist Joshua Pierce will most certainly bring a whole other level of personal inspiration into this work, which seems to be in a constant state of transformation.

Revelation: Music for the Harmonically Tuned Piano, Fri. & Sat., April 25 & April 26, Fri., May 2 at Faust Harrison Pianos, 205 W. 58th St. (7th Ave.), 212-489-3600.