IT didn't look like the rehearsal of a new violin concerto. Composer Tod Machover stood behind a music stand, expressively conducting and urging changes in tempo or volume. But in front of him was only one musician, violin soloist Ani Kavafian - plus someone hitting often inaudible single notes on an electronic keyboard and four technicians peering at computer screens or adjusting knobs.
A torrent of notes filled the darkened rehearsal room on the basement level of the Media Lab at the Massachusetts Institute of Technology (MIT) in Cambridge, Mass. At its center was Miss Kavafian's extraordinary playing, but around the edges was an aurora of accompanying sounds, some harmonious, some atonal, some percussive.
Other musicians would join in a week later, when Mr. Machover's concerto, ``Forever and Ever,'' premiered with the St. Paul Chamber Orchestra. But the soloist all by herself, playing the ``hyperviolin'' developed by Machover, was something of a one-woman orchestra.
``It works the right way - it draws attention to your notes,'' commented Machover during a break in the playing. The instrument being played by Kavafian bore only a slight resemblance to the Stradivarius she usually plays. The body of the hyperviolin is constructed from wood, much like a traditional violin, but it's slimmer and somewhat heavier - as Kavafian quickly pointed out after the vigorous rehearsal.
When not hooked up electronically, the instrument sounds like a muted violin. When it's plugged in, electronic gear inside the resonating chamber greatly amplifies the sound. Inside and out, the hyperviolin is fitted with small batteries, magnets, computer circuitry, and even a tiny antenna.
These electronic devices, plus other high-tech fittings on Kavafian's bow hand, feed a steady flow of information into three surrounding computers. Not just data about the musical sounds being produced by the soloist, but about her style of playing as well - the arch and flex of her wrist, the pressure on the strings, all of which contribute to her virtuosity.
The computers use that information to provide appropriate accompaniment from a bank of commercially available computerized instruments stored in one of the machines.
During the rehearsal, Machover constantly worked with his technical team to accentuate or reduce the contributions being made by various computer instruments that produce sounds ranging from traditional orchestral background to nontraditional, electronic tones.
The keyboardist, Machover explains, essentially gives signals to the main computer, telling it where the soloist is in the score. That helps the machine respond musically to the performer.
Machover says the array of electronic possibilities enveloping the soloist expands what that one individual can do. The goal, he says, is to enhance human creativity through technology, not subordinate it to the computer. By subtle changes in bow pressure, the soloist controls the electronic accompaniment.
``My hope is that a great musician like Ani will lend a type of magic, with the violin exploding into all kinds of expression,'' the inventor says.
Machover's ``hyperinstrument'' work has included past collaborations with cellist Yo Yo Ma and violinist Kim Kashkashian, as well as the recent concerto with Kavafian.
These efforts at MIT emphasize one facet of the electronic music field, according to Chris Chafe, a faculty member at the Center for Computer Research in Music and Acoustics at Stanford University in Stanford, Calif. That facet, he says, is the ``extension of traditional musical instruments into electronic possibilities.'' Mr. Chafe notes that the technology - sensors and other analytical tools - can be applied to any instrument: trumpets, say, as well as cellos and violins. (Machover is involved in developing a ``hyper'' drum system dubbed ``drumboy,'' for instance.)
Another aspect of electronic-music research is the creation of instruments that haven't existed before, says Chafe. In this regard, he says, the ``most far-out thing'' developed at Stanford sprang from a collaboration between the university's music department and the medical school. It's called ``bio-muse.'' This device converts bio-medical data about hand movements - or even eye movements - into musical sounds.
Another project at Stanford is the development of a ``forced-feedback piano keyboard,'' which promises to give synthesizer keys the touch and resistance of a fine piano and thus ``bring virtuosic piano technique into the field,'' says Chafe.
Machover, himself an accomplished cellist, says the violin concerto culminates his hyperinstrument collaborations with stellar talents like Ma or Kavafian. Down the line, he has a commission from the San Francisco Symphony to create a hyperinstrument for the whole orchestra. ``Ideally, with no wires on anyone's instruments,'' he says with a laugh. (Getting away from wires and cables has been a constant effort.)
Machover is also working on a work titled ``The Brain Opera,'' which he hopes to see performed at the 1996 Olympics in Atlanta. This ``opera'' involves having the audience itself participate in making music as it moves through a three-stage structure. People will become aware of their own responses to musical sounds, says Machover, and they'll be able to experiment with new sounds. Finally, he hopes, they'll work together toward a blending of many musical tones.
The production will be designed to simulate the mind's capacity to bring order out of chaos, says Machover - a kind of ``hyperinstrument for the public.''
How will it all work? Machover says that physically it won't be that complex, with ``maybe cameras looking or microphones listening.'' It's a vision in the making, but with a string of acclaimed hyperinstrument compositions and performances behind him, Machover has a pretty good record of turning visions into realities.