As long as there has been electronic music, composers have coupled it with live instruments, combining the freedom of real-time performance with a world of newly invented sounds limited only by imagination and available technology. Few do this as beguilingly or devotedly as Seattle composer Steve Scribner. His Stormsound Cycle, several years in the making, comprises 21 separate pieces lasting nine hours total, and he'll present the first performance of the whole thing this Saturday. It's based on field recordings of natural sounds—rain, wind, animal noises, and the like—some played as they are, some completely abstracted through electronic processing: "There's a bird call slowed down 1,000 times," says Scribner. "You can hear the individual vibrations." Alongside these prerecorded tracks, an ensemble of a dozen or so local contemporary-music performers will drop in and out in "guided improvisations" based on Scribner's "sound scrolls . . . music paper with landscapes drawn on them" and what he calls "melodicies," pitches written down with unspecified rhythms. Scribner himself will contribute on piano (played both conventionally and internally, directly tapping and brushing the strings) and an array of seashells, which provide a crisp, porcelain tinkle when struck with drumsticks. Also bringing new sounds to the mix will be Jay Hamilton and his homemade zither-like instruments, and Keith Eisenbrey, who coaxes sounds from objects like ping-pong balls and pieces of tubing. In excerpts from the cycle Scribner has previewed so far at the Seattle Composers Salon, he's demonstrated a refined ear for blend and contrast and a quiescent, Zen-like determination to, as John Cage put it, "let sounds be themselves." Listeners are invited to come and go, partaking of as much of the Cycle as they like.