Haptic Theremin

what is a theremin?

The theremin is one of the first electronic instruments, built in the 1920s. It is the only instrument that is played without touching it. It uses two antennas: a volume loop on the left, and a pitch antenna on the right. The antennas are controlled by the proximity of the hand using capacitance. The theremin can produce any frequency in the human range of hearing. It is very difficult to play because there is no tactile feedback or visual cues for proper hand placement.

the theremin in action

Carolina Eyck plays the theremin

earlier attempts to include feedback for a theremin

• Tracking hand motions using a powerglove or camera and provide a computerized graphical feedback for hand positioning
• Tactile feedback from a vibrating ring

haptic theremin project goals

• Use the Phantom Omni as musical controller based on the Theremin.
• Create a graphical interface to help orient the musician in pitch space.
• Provide tactile feedback to the musician using the Omni.

visual design specifications

• Free of clutter
• Accurate representation of Omni pointer position in the haptic playing space
• Visual representation of ‘frets’, pure pitches

haptic design specifications

• Easy pitch placement
• Force feedback for volume and distortion control
• Vibration feedback

audio design specifications

• High quality digital synthesis
• No perceived lag between hand motion and tone generation
• Add more audio control than classical Theremin

use of the Phantom Omni as a musical controller

haptic frets

vibration feedback

• Only one axis is needed for vibration feedback
• Vibration forces are felt in the Z-axis since this axis is the least sensitive in translating position to audio information

graphic design

audio design

• X, Y, Z axes and Buttons are translated into simple synthesizer commands and transmitted through the network using OpenSoundControl (OSC)
• SuperCollider audio language is used to create synthesizer

performance criteria

• Does the system meet the design criteria?
• Can it play the same range as a classical Theremin? Can it play more?
• Is it easy to find pure pitches?
• Can the musician FEEL the music?
• Do the graphics provide enough feedback to the musician?

graphics performance

• Graphics look great and are simple yet sufficient. Doesn't look cluttered
• Shadows with the option of cross-hairs provide additional help to the musician for graphical orientation
• On slower computers, texture mapping needs to be disabled or there is too much lag in the system

haptics performance

• Frets work well and don’t restrict the feature of continuous audio
• Additional force effects work, but take some adjustment to find what works well for particular musician
• Vibration feedback is difficult to achieve without the motors generating noise, and isn't very convincing to the performer

audio performance

• Basic audio features (pitch, volume, distortion) work well
• Capable of playing same range as a classical Theremin with ability to play additional ranges on the fly.
• Not taking advantage of additional 3 DOF (pitch, yaw, roll)

future ideas

• Recordable (track pointer path)
• Utilize extra 3 degrees of freedom for more tone options
• Song teaching routine (show which pitch to play at the right time)
• Different playing environments (non-cubical, more related to natural arm motion/swept out space)
• Improve vibration feedback

awards

Haptic Theremin received Honorable Mention in the 2005 SensAble Developer Challenge. The award was announced at SIGGRAPH 2005 and carries a prize of $1000.

paper

The paper describing this project can be obtained here:
Haptic Theremin: Developing a Haptic Musical Controller using the SensAble Phantom Omni

This paper was presented at ICMC 2006 in Barcelona and published in the Proceedings of the International Computer Music Conference, 2005.