Steer Sound with a Tether
Series: alt.ctrl activities; builds on Gametrak and Wii controllers; Spatial arrangement
In the paper, a ceiling-mounted Gametrak with an inertial sensor on its tether (a Wii remote) drove a loudspeaker array whose directivity can be programmed: the tether steered narrow beams of sound, and striking gestures played a virtual swinging gong.
The same ideas work with any sound spatialization technology: loudspeakers around the listeners, and software that places sounds among them, for example by panning or by Ambisonics.
Materials
| Item | Amazon | eBay |
|---|---|---|
| A Gametrak controller (originally sold with two gloves and a footswitch) | search | |
| An inertial sensor that can hang on the tether (the paper used a Wii remote) | ||
| A sound spatialization system: loudspeakers around the listeners, and spatialization software | ||
| A computer with Max/MSP or Pd |
Tools
- Tools not yet listed.
Skills
- Skills not yet listed.
Instructions
- Mount the Gametrak above the playing area, and attach the inertial sensor to a tether.
- Read the tether's direction and length, and the sensor's motion.
- Steer: map the tether's direction to the direction a sound comes from in the spatialization system.
- Strike: detect striking gestures from the sensor's motion, and play a virtual gong whose sound swings around the room after each strike.
Variations
- Hang the sensor in a bob, as in the Pendaphone.
Related resources
- Musical Applications and Design Techniques for the Gametrak Tethered Spatial Position Controller, Freed and others, SMC 2009, section 4.3
- Applications of Environmental Sensing for Spherical Loudspeaker Arrays: the original setting, a 120-channel spherical loudspeaker array
- Ambisonics (Wikipedia)
Coding Prompt Build Block
A prompt to give a coding assistant, to start the code for this activity. Copy the box, answer its questions about your board and pins, and test what comes back on the bench before you rely on it.
I am building "Steer Sound with a Tether", the activity at https://adrianfreed.com/steer-sound-tether.html.
Write a Max or Pd patch, or a program, that reads a ceiling-mounted Gametrak's tether, its direction and length, and the motion of an inertial sensor hung on it (the paper used a Wii remote).
Steer: map the tether's direction to the direction a sound comes from in the sound spatialization system, by panning or Ambisonics. Strike: detect striking gestures from the sensor's motion, and play a virtual gong whose sound swings around the room after each strike.
Libraries to explore:
- o.io.gametrak (CNMAT MMJ Depot): CNMAT's Max patch for the Gametrak: it opens the device and outputs /left/x, /left/y, /left/z, /right/x, /right/y, /right/z and /footswitch, the angles scaled from -1 to 1 and the extensions from 0 to 1 (https://github.com/CNMAT/CNMAT-MMJ-Depot/tree/master/patchers/io/gametrak)
- odot (CNMAT): the o. objects for Max and Pd that o.io.gametrak is built from, with OSC bundles as their data type (https://github.com/CNMAT/CNMAT-odot)
- Max hi object: reads human interface devices, such as game controllers, in Max (https://docs.cycling74.com/reference/hi/)
- Pd hid external: reads USB HID devices, such as joysticks and gamepads, in Pd, on GNU/Linux and macOS (https://github.com/pd-externals/hid)
Before writing anything, ask me what I am using: the board and its pins, or the software (such as Max, Pd or Python), and check its documentation for what this needs. Put the pin numbers, ranges and other settings in one block at the top, each with a comment. Say which of the libraries above you use, and why. Start with a test that shows the raw readings, so that I can check the wiring and the ranges before the rest.
This activity by Adrian Freed is licensed under Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0): you may share and adapt it with attribution, for non-commercial purposes such as personal projects and teaching, and you must share adaptations under the same licence. Product names and links belong to their suppliers.