The early electronic interfaces for bowed string instruments processed sound from pickups, adding amplification and effects. A classic example is Max Mathews’ violin, which used piezoceramic bimorph pickups with resonant equalization. Piezoelectric pickups are also used on an even more unconventional electric string instrument, the Gravikord, which Bob Grawi developed from the kora, a West African folk harp. Many other artists have made various unconventional electric string instruments with pickups of different kinds. This category has included some infamous behemoths, such as the “Lyra Sound Constellation” (156 microtonally-tuned wires stretched 15-20 feet from floor to ceiling) built in Los Angeles by George Landry in the early 80′s and played by Michael Stearns and Craig Huxley’s 18-foot “Blaster Beam” built around the same time and used in many Hollywood soundtracks. A recent example in the world of alternative rock is the Boston band Neptune, a group of sculptor-musicians who build their own instruments, show them in art galleries, and perform live with them. Banjos, harps, and all kinds of other string instruments can be found today in electrified versions. Although the audio signals from these devices can likewise be processed extensively with effects that can change their sound enormously (witness, for instance, the electric harp performances of Zeena Parkins), bringing them into the world of MIDI still typically requires one isolated pickup per string and signal processing algorithms tailored to the particular instrument’s response.
In general, traditional stringed instruments (e.g., violin, viola, cello) have followed the guitar along a similar, but less trodden path toward becoming true electronic music controllers. Although the complicated and dynamic nature of a bowed sound makes fast and robust pitch tracking and feature extraction difficult, many researchers have developed software with this aim; commercial MIDI pitch-tracking retrofits are also manufactured for violins, violas, and cellos. Zeta, for instance, has built a full line of MIDI stringed instrument controllers over much of the last decade, and still manufactures MIDI controller electronics and retrofit pickups for both its own and 3rd party instruments.
Motivated by the vast world of sonic expression open to a skilled violinist, many researchers go beyond analyzing the audio signals, and build sensor systems to directly measure the bowing properties. Chris Chafe, of the CCRMA at Stanford, has measured the dynamics of cello bows with accelerometers and the Buchla Lightning IR tracker. Peter Beyls, while at Brussels University in 1990, built an array of IR proximity sensors into a conventional acoustic violin, measuring fingering position and bow depression. Jon Rose, together with designers at STEIM, Amsterdam, built interactive bows with sonar-based position tracking and pressure sensors on the bow hair.
At the MIT Media Lab, we have designed several systems for measuring performance gesture on bowed string instruments. These efforts began with the Hypercello, designed by Neil Gershenfeld and Joe Chung in 1991, and continued with the Hyperviolin, designed by the author in 1993. In addition to analyzing the audio signals from each string and measuring the fretting positions with a set of resistive strips atop the fingerboard, the bow position, placement, and pressure were measured through capacitive sensing, which is much less sensitive to background than most optical or other techniques. The Hypercello and Hyperviolin have been used several times in performances of Tod Machover’s compositions, played by several soloists, including Yo-Yo Ma and Ani Kafavian.
Of course, inventors all over the world have been adapting technology to turn non-western stringed instruments into electronic music controllers. Perhaps one of the more extreme is Miya Masaoka’s “Koto Monster”, a 6-foot-long, hollow-bodied, 21-string, harp-like digital instrument that she developed at the Dutch STEIM center.
From American Innovations in Electronic Musical Instruments
by Joseph A. Paradiso
© 1999 NewMusicBox