the Stretch Harp

Recently I was tasked with building a new instrument for musical expression as part of an assignment at Bournemouth university as part of my music and audio technology course. This consisted of two key elements, one to physically build the instrument and secondly to create a synthesis engine for it.

Frame of the Stretch Harp.

String attachment of the Stretch Harp.

As a bit of background, each year there is a conference to show new interfaces for musical expression, The NIME show, many academics from around the world build new devices and present papers written about the field. A proceedings archive can be found here showing all the documents presented at the conference over the years. So what is a NIME? While its hard to give a definition in short, its should be a novel way of controlling and manipulating sound that allows for a performer to extend and express their musical intention.

Guide holes of the Stretch Harp.

I created something I call the Stretch Harp, it is played by pulling on strings, in turn pulling the shat of a slide potentiometer, this is then feed into an Arduino and then to Max 7 where the synthesis engine resides. In addition to the 14 strings there are two ultrasonic distance sensors and a sustain pedal.

Tension system connecting the strings to the slide potentiometers of the Stretch Harp.

Some of the 14 potentiometers used in the project.

The system is mounted in an aluminium frame built with a 99p junior hacksaw, a £12 electric drill and a few pencil files, so as a result the physical build didn’t come out as precise as I would have liked. However still very usable and sturdy.

Close up of the paracord used in the project

Overall I happy with the outcome however I would like to expand on it further perhaps building a second prototype using springs rather than rubber bands, and adding more strings to give two full octaves. Here is a short video of the device.