Encased in a wooden box resembling a shoeshine kit, Hopkin's invention works a little like an old wax cylinder phonograph, except that the diameter of the "cylinder" tapers from 12 or so inches to the size of a silver dollar. By pressing guitar-pick-like pieces of plastic against the motorized contraption's spinning rubber treads, Hopkin elicits a series of desperately high-pitched screeches.
"It sounds a lot like acid guitar," says the 44-year-old inventor. Actually, it sounds more like a family of crows being led through a wood chipper, but the whatsit provides an admittedly valuable lesson in acoustic theory. As with most of his creations, Hopkin hasn't bothered to christen this one, though he says he's thinking about calling it a "rotary rasp."
Bart Hopkin is the founder and editor of Experimental Musical Instruments, a quarterly journal "for the design, construction, and enjoyment of unusual sound sources." After 12 years of providing his obscure but beloved periodical for 1,400 avid musicologists around the globe, Hopkin has undertaken his first mass-market project, the CD-and-book box set Gravikords, Whirlies, & Pyrophones: Experimental Musical Instruments.
"There are a lot of beautiful coffee-table books of historical and early instruments," explains the dedicated hobbyist. "I thought there should be a book like that for contemporary instruments," which is what he calls the percussive oddities and scrapheap hybrids to which EMI devotes its pages.
Having graduated from Harvard with a degree in folklore and mythology (specializing in ethnomusicology), Hopkin worked for several years as a traditional music teacher. "Because it was required for the teaching positions, I could play all the standard instruments," he says, enunciating each word with a thespian's precision. "In theory, I could teach your kid to play the tuba."
But his real interests lay with musical territories foreign to Western ears -- tunings other than the standard 12-tone system, unconventional song structures, "nonmusical" sounds explored as music in and of themselves.
"Art is nothing but self-indulgence," he says, "and I believe people should be self-indulgent."
Captivated by a discussion on KPFA radio with a woman who had established Autoharpaholic, a newsletter for people with an inordinate passion for the autoharp, Hopkin was inspired to create a similar publication for readers who shared his curiosity about the endless possibilities of sound.
"I can't remember exactly what on earth I did, how I found my first subscriber," he says now. Still, he has managed to establish EMI as the ranking (and possibly only) authority on this esoteric subject. With the faintest hint of pride, Hopkin suggests that "creative organology" -- the study, according to him, of experimental musical instruments -- is on the rise.
"Is it there because I'm looking, and it's been there all along?" he asks rhetorically. "Or is there actually more going on than in previous decades? I don't know."
A few of the three dozen inventors featured in the Gravikords book have names that are relatively well-known to adventurous listeners, such as the Russian physicist Leon Theremin, the headstrong avant-gardist Harry Partch, or Luigi Russolo, author of the influential 1916 essay "The Art of Noises." While Hopkin acknowledges that their inclusion was a concession to his publisher, he also argues that it's helpful to provide some context for the other artists' work. If Partch's name is familiar but interested parties find themselves asking what his compositions sound like, he says, "it's a service to answer that question."
The Gravikords CD features a vast array of eccentric sounds, from Partch's "And on the Seventh Day, Petals Fell in Petaluma" to Jean-Claude Chapuis' ethereal glass instruments, from the theremin virtuosity of Clara Rockmore to Wendy Mae Chambers' eccentric interpretation of "New York New York," squeezed out on her "car horn organ."
Unlike some of the iconoclasts he's written about, Hopkin says he retains his respect for "traditional" music: "I love Mozart. I still have a gig playing conventional instruments for dinner music [at a Point Reyes cafe], and nobody wants to hear Harry Partch for dinner music."
Though he admits he's not very up to date on pop music -- "Not because I have anything against pop music, I'm just too disorganized" -- he is at least somewhat familiar with the recordings of fellow Northern Californian Tom Waits, who was invited to write a foreword for the Gravikords book. "He loves this kind of stuff," Hopkin says. "He goes to junkyards and finds interesting stuff. And he sometimes shows up at jam sessions of weird instrument makers, and brings his absolutely distinctive flavor."
The zany array of instruments that turns up at such events isn't exactly anybody's idea of a symphony orchestra, Hopkin says. "For one thing, they're probably not in tune with each other. ... You're hoping you can find some common ground, and a lot of the time you end up with music that isn't so great. But often enough, you find musical territory you never would've been able to find, tonalities that nobody's been able to arrive at. It's a wonderful communal experience."
Goaded by his visitor, Hopkin demonstrates a few more of his own contrivances, most of which are made from common household items -- balloons, rubber bands, styrofoam cooler lids. Since launching EMI, Hopkin says he is less inclined to regale his audiences with the childlike cry, "Look what I built!" "But I still enjoy showing them off," he laughs. Kneeling in his jeans on the office's worn, squash-colored shag, Hopkin begins plucking at a traylike apparatus sprouting a few dozen wire antennas, which emit mellifluous boinging sounds. He also plays a few notes apiece on a clarinetlike instrument shaped from dried seaweed, a valved "reed" instrument fashioned from a cardboard shipping tube, and a slide-whistle-style flute pitch-controlled by a curling slice of lightweight wood. "I like the slide whistle a lot," says the inventor. "People associate it with something stupid -- when the cartoon character's pants fall down -- but it can be the most haunting instrument." It is, in fact, a haunting sound that he produces, as rain drips from the plentiful leaves outside.
"I have very little ambition," Hopkin says, "but when I do something that I think shows off one of my instruments well, I'm happy, and I might even try to convince my wife she should come listen to it.