TONE is an analog audio feedback circuit with a tree-like array of three electret condenser microphones, resonant 4Ω loudspeaker, 9V amplifier, and cylindrical waveguide. Acrylic 'leaf' microphone mounts are suspended at the end of each cylindrical 'branch.' Acoustic feedback is situated by arranging the loudspeaker upward toward the mic array. As pressure waves propagate upward from the loudspeaker, sound is filtered through the pipes before arriving at the mic array, thus introducing non-linearities and expressive opportunities.

Prospects such as air-gapped proximity filtering and intuitive physical interactions are apparent for human interaction. When participants walk around the device, a Helmholtz-like standing wave is produced intermittently in the room. This is a result of acoustic reflectivity and external sound energy. The fundamental frequency derives from the resonance of the glass sphere mounted above the loudspeaker.

Other system frequencies can be activated by focusing energy around a particular microphone 'leaf' with one's hand in close proximity. Higher frequencies are based on cylinder length and electronic flow. Participants can perceive that environmental sounds are immediately transformed and influence other resultant resonances. This instrument is part of an ongoing audio feedback project, SHAPE, with support from The Center for New Music and Audio Technologies.

> Jason Cress, Graduate Student Researcher

> SHAPE, Sound and Habitat Audio Prototyping Environment

Additional Project Images