In this day and age artists wrangle for grants to keep their work alive. But when Trimpin brings his unusual sculpturelike sound-making apparatus before a music grants committee, it prompts mostly head-scratching. He relates the typical scenario: "They'd say, 'Oh, this is sculpture. You have to go to visual arts.' And when I'd take it to them, they'd send me back to music." Trimpin eventually found a home in the comparatively new "interdisciplinary" category. For someone who won a 1998 MacArthur Foundation Genius grant (that's $280,000 over five years), he still falls through the cracks in terms of public awareness. "I don't get much press because, in general, the music-critic society is very careful," he explains. "They haven't developed the language of how to review or approach my music."

Trimpin's obscurity is additionally ensured because he refuses to record his performances or installations. "Most of my work is spatially oriented," he says. "I use space to move the sound around. Everyday technology doesn't exist to capture sound-in-the-round, to make that experience reproduceable for everyone. It's a dilemma."

Trimpin will make a special local appearance in Miami this week; four performances of his M.I.A.M.I. Klangflotte will be part of the Subtropics New Music Festival. The Klangflotte (German for sound fleet) is a set of six rickshaws that ride around producing odd symphonies. Three of these vehicles will have Trimpin's sound machines attached (percussive horns and xylophonelike noisemakers), and the sound will be computer-controlled via radio signals sent by the artist, who will also be riding one of the bikes. The other three bikes will carry musicians in the back ("trombone and sax, probably"), improvising along with his machines. Because the setting is important to the sound itself, that too will vary. "Two are in open space, at Homestead and in Fort Lauderdale. The others will have buildings for the sound to bounce off. Open space is a little better," he says. One special performance will be more linear: His contraptions will make a procession down Lincoln Road Mall.

The elaborate arrangement of sound and space is one reason why a recording of his work will always be incomplete. "Even though we only have two ears, we perceive in multidimensions," Trimpin says. Occasionally though, he'll produce something that, under the right circumstances, could be recorded by conventional means. For instance the piano-playing device he originally developed for avant-garde composer Conlon Nancarrow. Nancarrow's piano pieces require vast intervals and complex rhythms that are impossible to play with only two hands. Although a player piano can perform Nancarrow's numbers, not every performance venue has one, and these antique instruments are hard to come by. Trimpin was invaluable in producing a machine, the IPP7152, an "instant prepared piano." His elaborate construction sits on top of any grand piano and not only plays the keyboard, but replicates all sorts of prepared piano techniques (bowed piano strings, unusual hammer methods) as well. Recording the IPP7152 will have to wait, however. "I wanted to find the perfect space for it. We found it, but I'm too busy," Trimpin notes

There's another reason releasing CDs is a low priority for Trimpin: It's not his favorite medium. Audiences now accept, without question, music or sound emitting from tiny speakers placed everywhere, from Walkman headphones to drive-up windows. In fact we forget that there once was a world where man-made sound was a rarity. Trimpin, on the other hand, still thinks about it. He also prefers large scale -- the antithesis of how the vast majority of music is recorded and played today.

"We're still using the basic design of the speaker, which is over 100 years old. Sound used to be designed to fill up the concert hall," he says, speaking with obvious fondness for the history of mechanical music. "With the introduction of the record player, everything shifted toward mass entertainment with recorded sounds. Before that there were terribly sophisticated dance organs as part of the industry. When recorded sounds came in, all that technology died. And with that we also forgot what you can do with sounds that come from different materials as sources."

Exploring that world of different materials provides further grist for Trimpin's creativity, from the Fire Organ (a keyboard that uses shooting flames to produce sound) to the Liquid Percussion, which outputs precisely regulated water droplets onto thin glass resonators.

"Dry ice screams when you put it on certain metals," he says. "Or you can heat shrinkwrap with a hair dryer and rub your fingers on it." He also says you can shift the pitches on instruments by playing them in environments of different gases, such as helium. It's no surprise to anyone who's horsed around with balloons, but it's not exactly a technique often used in music-making.

He's also taken traditional instruments and given them expanded life. One concert used clarinets that had extra holes, so they played microtones -- notes between the standard notes on the scale. Of course players only have ten fingers, so he controlled the stops with a computerized, Rube Goldberg-esque contraption. In a brilliant conceptual move, he levitated gongs using magnets; when they were struck, they rang for extended periods of time, having nothing holding them to dampen the sound.

There is a major downside to all this noise. Many years ago, on a quest for quiet, untouched soundspace, he took a trip to Alaska. There he made a sobering discovery. "You cannot find a spot anywhere in the world where you can hear sounds that are not interfered with by the modern world," he says. Airplanes and outboard motors litter the soundscape in the same way that structures encroach on the natural landscape. Even though there are places in the world that look untouched, there is nowhere that will sound exactly like the world did 100 years ago. "This is a tremendous change in how we perceive," Trimpin says. "People have extreme problems with hearing. Your frequency response is reduced by 50 percent by the time you hit 40 or 50 [years of age]. It's sad to see that we are losing our hearing after thousands of years of evolving this supersensitive ear. Human evolution can't keep up with the modifications we've made in our environment."

The M.I.A.M.I. Klangflotte performs on Friday, April 9 at 7:30 p.m. at the Homestead Town Square in Losner Park. Call 305-242-4814 for more information. On Saturday, April 10 at 2:00 p.m. the Klangflotte hits the Miami-Dade Cultural Plaza (101 W Flager St, 305-375-1727). Later on Saturday, at 5:00 p.m., it takes to the Lincoln Road Mall on Miami Beach (305-674-8278). Sunday, April 18 at 3:00 p.m. it moves to the Riverwalk in Fort Lauderdale (954-468-1541). All performances are free.