My gesture-controlled water glass is an interactive performance system that extends the sonic possibilities of an ordinary instrument which many of us have spent dinner parties tinkering with from childhood.  This instrument processes live acoustic sound produced by a water glass (eg. rubbing the rim, tapping the sides, hitting the stem and etc.), working from the metaphor of how we interact with the acoustic water glass itself.  Three physical gestures—stroking with two fingers, grabbing, and dipping finger water—control this processing via interactions ranging from simple triggering to more complex, time-stretched controls.   This system includes a second-order analysis that responds to the velocity of changing between physical gestures performed on the water glass, creating affordances and constraints that evolve over time.  As a dynamic system, the user’s interaction necessarily responds to changing constraints of the water glass, creating a space to reimagine the life of the everyday object.

Sound Design

Seeking inspiration from the beautiful pure tones native to the acoustic water glass, my instrument can create lush ambient textures to complement the idiom.  Stroking the glass with two fingers creates a pitch-bend and alters the delay time between intial sound and processed sound, grabbing the glass sounds pitch-shifts the sound based on the harmonic series, and dipping a finger in water spatializes the sound as if the listener were inside the water-filled glass itself.  Rapid shifts between gestures open delay lines, leading to a peak of sonic activity.  After this peak, the instrument shifts the timing of delay lines and introduces a gradual low-pass filter as a constraint. 

All sound design was programmed in MaxMSP, via a simple interface as shown below:

 

Technical Details

Building off of Disney’s Touche sensor, and Mads Hobye’s Touche for Arduino Instructable, my project uses a Touche sensor for gesture recognition.  Initial calculations of the swept capacitive frequency sensing are done in Arduino, which communicates just the X and Y position of the frequency to MaxMSP through the serial port. See below for a list of materials, the circuit diagram of the sensor, and my breadboard realization:

HARDWARE:
Resistors: 10k, 1M, 3,3k
Capacitors: 100pf, 10nf
Diode: 1N4148
Coil / inductor: 10mH
Alligator clip

 

Sound processing is enabled through a simple contact mic made from a piezo and hacked audio cable that connects to an audio interface (left).  Both Touche sensor and contact mic are secured with a simple stand made of wood I built (right).

Files Available for Download