The aim of the Hackable Instruments project is to create instruments that can be easily tweaked by the player to find interesting new directions for producing flavorsome tones, without any specialist knowledge of electronics or engineering, while also aiding in the development of distinctive playing styles. Project members Andrew McPherson and Victor Zappi have designed and built a deliberately simple instrument that produces sounds when a player's fingers touch, slide or tap a capacitive sensing strip on one of the wooden cube's faces.

Last year, McPherson hit Kickstarter with a system that placed capacitive touch sensing strips atop the keys of a piano-style keyboard to give players continuous dynamic or expressive control without having to reach for a pitch wheel, buttons or dials while playing. TouchKeys was aimed at folks who already knew their way around a piano keyboard, but this latest electronic instrument hack doesn't require any prior playing experience at all.

"We're interested in studying how humans use technology to make music," the Queen Mary University of London (QMUL) told Gizmag. "The cube instrument is designed to be one of the simplest possible digital musical instruments, producing only a very limited range of sounds (one note or a few notes, with a few variations in timbre). Constraints can be a powerful motivator for creativity – think about someone turning a pair of spoons or a washboard into a musical instrument – and by creating a very constrained instrument, we're studying what performers come up with in response."

The battery-powered 8-inch wooden cube comprises a two-dimensional capacitive touch sensor strip (actually the front part of a TouchKeys sensor) with a force-sensing resistor (pressure sensor) underneath on one of the cube's faces and an output speaker on another. Inside, there's a BeagleBone Black development board with an audio interface that runs Linux and some custom software authored by Zappi.

The team created two versions of the cube. The software of one generated sound based on pressure only, and the other produced small variations in frequency depending on the location of the touch on the sensor strip. Both instruments gave players a blank sonic canvas on which to explore new, and perhaps even very personal, playing styles.

The cubes were put through their paces by 10 volunteers from a wide range of musical backgrounds, including classically-trained musicians and electronic music hackers, at an informal QMUL gathering at the end of January.

"We tried not to suggest any particular 'right' ways of playing, either in the design of the box or in any of our instructions," said McPherson. "What we found was a startling range of playing styles, including many techniques we hadn't anticipated, such as playing on the wooden box, filtering the speaker with the hand, even licking the sensor to produce a sustained tone from the residual moisture. This was very interesting because it confirmed one of the principles we set out to test, that performers will discover personal ways of using an instrument that differ from the designer's intentions."

"Another interesting result came from comparing two types of instrument," he continued. "One version of the box had just one degree of freedom (pressing harder changed the timbre), where the other one had two degrees of freedom (where you touch controlled the pitch within a narrow range). We found that musicians who got the two degree-of-freedom version tended to explore unconventional features of the instrument less, and they actually seemed to see the instrument as being more constrained. It suggests that they saw the limited pitch range as the dominant constraint, where other players who didn't have pitch at all simply looked for other techniques to use."

More features for the cube are being explored, and the team plans to release open-source design materials to help musicians take the concept further and cater for reinterpretation, or even physical hacking. The fruits of the 15-month Hackable Instruments: Musical Interface Design for Appropriation, Modification and Creative Destruction project, which is receiving almost £100,000 (US$170,000) in funding from the Engineering and Physical Sciences Research Council (EPSRC), will be showcased at a special public performance later in the year.

The video below explores the project in more detail.

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