Can You Here the Shape of a Drum?
is a project that proposes to link two parallel lines of research: the three-dimensional controller called the Radio Drum and the class of synthesis techniques known as physical models. The Daniel Langlois Foundation partly supported the research and development necessary to link the Radio Drum with physical modelling synthesis. Schloss then intends to create a new performance work, Can You Hear the Shape of a Drum?,
that will showcase these ideas and techniques. The software developed for this project will also be made available to others in the field. The following is a text by Schloss describing the instruments he is using in his research and the techniques he wishes to explore.
The Radio Drum and the Tactex Pad, by Andrew Schloss (1)
was certainly one of the most important musical inventions of the 20th century. Based on similar physical principles, the Radio Drum, invented at Bell Labs by robotics engineer Bob Boie in the late ’80s, can be considered to be a descendant of the Theremin. It uses capacitive sensing; a radio-frequency voltage source is conducted from the performer’s mallets or sticks, and is received on the drum surface beneath. The two sticks are differentiated by using different frequencies for each one. The x,y,z position of the sticks can be polled at arbitrarily high sampling rates, allowing for extremely high temporal accuracy if desired.
The Radio Drum is a three-dimensional controller that gives points in three-space, with sufficient resolution to measure continuous changes in x, y, and z [Boie, et al 1989] (2)
. Therefore six degrees of freedom are exploitable, in a very natural context. It is important to note that while knowing position in space is interesting, it is imperative to be able to accurately detect with high temporal accuracy (from these position data) specific physical behaviour on the surface of the drum such as percussive effects, rolls, flams, bounces, scrapes, muffs, etc.
The tactex pad is also a multidimensional sensor that has 3*n degrees of freedom where n is the number of fingers on the pad at any given time, based on the pad's ability to report x,y and pressure for multiple fingers. Tactex’s technology involves a "Smart Fabric" that is able to sense and measure pressure at multiple points of contact. Originally developed for the Canadian Space Agency, it consists of an array of fibre optic sensors embedded in a thin foam rubber-like material. The touch sensitivity and performance of these materials are similar to that of human skin. It allows the computer to track the position and pressure of each finger placed on its surface, and hence the gestures made by the fingers.
The first step is to make the already-existing software and analysis tools created at UBC by Dinesh Pai and Kees van den Doel usable in a musical context, and run in real time. In order to do this, we need to port portions of the original implementations which were in JASS (a Java Audio Synthesis System for programmers) [van den Doel, et al 1998] (3)
to Max/MSP where they can be used by anyone in the community, have better real-time control of parameters, and also have existing support for Radio Drum and Tactex integration in Max/MSP.
Next, we will begin the un-simulatable process of making the system musical. By un-simulatable, we mean it is necessary to physically play the instrument when "tuning" the algorithms. This is an effective way to create something usable and musical, responding in subtle ways to small changes in input, and thus fully exploiting the musician’s performance skills that were honed over many years.
A variant of the original Radio Drum called the Radio Baton
has been produced by Max Mathews at CCRMA Center for Computer Research in Music and Acoustics (Stanford University) since the early ’90s. The Radio Baton is designed for conducting and does not have as stringent temporal requirements as the drum. However, both the Radio Drum and the Radio Baton use the same sensing technique; the Radio Baton has been improved due to research conducted at Interval Corporation in Palo Alto in the late ’90s. The original instrument from Bell Labs was a serial device; Mathews’s Radio Baton is a MIDI device, and we propose, for the next generation instrument, that it be an Ethernet device. It will be one of the first Ethernet instruments that we know of, but there will surely be others.