Jack Straw Productions, 4261 Roosevelt Way NE, 634-0919.

Through April 27.

Let's start with a fusty generalization: Old systems that have worked more or less well over a long period of time eventually become invisible, though no less functional. For example, you don't think about balancing your checkbook in base-10 mathematics, you just do it. This system's appropriateness goes right down to the biological level--10 fingers, 10 toes--and it rarely occurs to anyone that there are other systems of math out there, let alone one that might be more efficient. And you know that calling old systems into question results in all kinds of unbalance--from light seasickness to full-scale agony. If you don't believe me, may I respectfully point you in the direction of the metric system?

I bring this up because I suspect that in Trimpin's work a lot of everyday tools and assumptions are being knocked sideways. I don't have any idea what those things might be, but there's always something that tells me some foundation is being shaken. It registers as a low distant rumbling, an atmospheric buzz, a tingling in the extremities, but it's nothing I can identify, partly because I don't possess the language to do so.

Trimpin's new installation at Jack Straw, Klavier Nonette, is sweet, really, but never so sweet as to deceive you into thinking it's less than it is. It consists of nine toy pianos placed around the room, which are activated when someone puts a quarter into a console and chooses a piece of music. The pianos then play one of about 40 songs, from Liberace's "Alley Cat" to John Cage's 1948 "Suite for Toy Piano" to a number of pieces commissioned specially for the project. Thanks to electromechanical hookups I can only guess at and musical logic I can't even imagine, the notes are divided among the pianos so that the result is fragmented, jumpy, but the result is undeniably whole. You haven't lived until you've heard the notes of "Alley Cat" jump psychotically from one tiny piano to the next, as if these little instruments were ready to leap off their pedestals and join the conga line.

Like other works by Trimpin, the result is sound that is sculptural, dimensional, enclosing, and unexpected--more accumulative than linear, a far cry from the muzzy mush you often get when people show sound sculpture. It's also faintly creepy, in a lost-in-the-funhouse way. You can stand by a piano for a good 30 seconds in which nothing happens, and then suddenly it's pounding arpeggios, chords, or just a single note. Part of this, of course, is an effect of scale--not musical, but proportional--that is, of tiny little children's pianos performing important work, and sometimes with a good deal of violent energy, both amusing and unsettling.

Of course, your experience in the three-dimensional world of sound is only the tip of a great looming intellect. Trimpin's explanation is that "the timbre and sound of toy pianos... resembles somewhat the intonations of non-Western systems and our ears respond to the more natural harmonic spectrum in comparison [with] the precise tuning of our system of music. To achieve certain acoustical layers, it is necessary to use multiple instruments (with the same octave range) strategically placed around the room." What this meant to me was a general upsetting of things that normally go together: Chords are divided between instruments; the distinction between left-hand and right-hand parts becomes arbitrary, or if not arbitrary, then thoroughly rethought.

And more than that, I can't say. Like Trimpin's other work, this one has an effect on me of exquisite bafflement--that is, I'm baffled and happy about it. The philosophies present in his work (the remoteness of the musician from the instrument, the dedication to acoustic instruments, with the very visible exception of his electric guitar sculpture at EMP) are the artist's variables to play with, and what's left for us is mostly pleasure, with perhaps the residue of shock that the musician can be so present and absent at the same time. This is something we're pretty much used to, since most of our music comes to us in recorded form, but like any good revolutionary system, Trimpin's work throws us back on first things.