A human musician interacts with sensor(s) that detect physical activity such as motion, acceleration, pressure, displacement, flexion, keypresses, switch closures, etc. The data from the sensor(s) are processed in real time and mapped to control of electronic sound synthesis and processing.
Diagram of processes (ovals) and data (rectangles) flow in a sensor-based musical instrument.
This kind of application is often realized with Heterogenous Distributed Multiprocessing on Local Area Networks, e.g., with the synth control parameters sent over the LAN to a dedicated "synthesis server," or with the sensor measurements sent over the LAN from a dedicated "sensor server". There have also been many realizations of this paradigm using OSC within a single machine.
- Wacom tablet controlled "scrubbing" of sinusoidal models synthesized on a synthesis server. (Wessel et al. 1997)
- The MATRIX ("Multipurpose Array of Tactile Rods for Interactive eXpression") consists of a 12x12 array of spring-mounted rods each able to move vertically. An FPGA samples the 144 rod positions at 30 Hz and transmits them serially to a PC that converts the sensor data to OSC messages used to control sound synthesis and processing. (Overholt 2001)
- In a project at the MIT Media Lab (Jehan and Schoner 2001), the analyzed pitch, loudness, and timbre of a real-time input signal control sinusoids+noise additive synthesis. In one implementation, one machine performs the real-time analysis and sends the control parameters over OSC to a second machine performing the synthesis.
- The Slidepipe
- Three projects at UIUC are based on systems consisting of real-time 3D spatial tracking of a physical object, processed by one processor that sends OSC to a Macintosh running Max/MSP for sound synthesis and processing:
- In the eviolin project (Goudeseune et al. 2001), a Linux machine tracks the spatial position of an electric violin and maps the spatial parameters in real-time to control processing of the violin's sound output with a resonance model.
- In the Interactive Virtual Ensemble project (Garnett et al. 2001), a conductor wears wireless magnetic sensors that send 3D position and orientation data at 100 Hz to a wireless receiver connected to an SGI Onyx. This machine processes the sensor data to determine tempo, loudness, and other paramaters from the conductor; these parameters are sent via OSC to Max/MSP sound synthesis software.
- VirtualScore is an immersive audiovisual environment for creating 3D graphical representations of musical material over time (Garnett et al. 2002). It uses a CAVE to render 3D graphics and to receive orientation and location information from a wand and a head tracker. Both real-time gestures from the wand and stored gestures from the “score” go via OSC to the synthesis server.
- In Stanford’s CCRMA’s Human/Computer Interaction seminar (Music 250a), students connect sensors to a special development board containing an Atmel AVR microcontroller which sends OSC messages over a serial connection to Pd (Wilson et al. 2003).
- Projects using La Kitchen's Kroonde (wireless) and Toaster (wired) general-purpose multichannel sensor-to-OSC interfaces.
- Projects using IRCAM's EtherSense sensors-to-OSC digitizing interface
- The BuckyMedia project uses 3d accelerometers employing OSC over WLAN (box developed by f0am) to transmit the movements of several geodesic, tensile or synetic structures for audiovisual interpretation.